Advancing Composite 

Foam Core Technology


Read the answers to our most frequently asked questions by clicking on the tabs below.


Abrasion Resistance: What is Abrasion Resistance? The ability of a material to withstand abrasion without appreciative erosion.

Absolute Humidity: What is Absolute Humidity? The ratio of the mass of water vapor to total volume of an air sample. The I-P units are pounds of: moisture per pound of cubic foot of air and the SI units are grams or kilograms of moisture per: cubic meter of air.

Absolute temperature: What is Absolute temperature? Absolute temperature is the temperature expressed in degrees above absolute zero. Absolute Zero is the lowest temperature theoretically attainable. The temperature at which there is no more heat and no longer molecular movement. The zero point of the scale is 459.6 degrees below the zero of the Fahrenheit scale and 273.2 degrees below the zero of the centigrade scale.

Absorptance: What is Absorptance? The ratio of the radiant flux absorbed by a body to that incident upon it.

Absorption (water): What is Water Absorption?  Absorption is the action of a material in extracting water from the atmosphere often leading to a physical change in the absorbent.

Absorption (thermal): What is Thermal Absorption? Transformation of radiant energy to a different form of energy by interaction with matter.

Acidity: What is Acidity? The quality of a material to be acidic (pH under 7) when exposed to moisture or water producing a red/pink reaction to litmus paper. In the insulation industry, materials with pH between 6 and 8 are generally considered non-acidic and non-alkaline.

Acoustical Treatment: What is Acoustical Treatment? Application of absorbing insulation for sound control.

Acrylonitrile-Butadiene-Styrene (ABS): What is Acrylonitrile-Butadiene-Styrene (ABS)? A high-impact plastic.

Additive: What is an Additive? Any substance added to another substance, usually to improve properties, such as plasticizers, initiators, light stabilizers, and flame retardants. See also filler.

Adhesion: What is Adhesion? The state in which two surfaces are held together at an interface by mechanical or chemical forces, interlocking action, or both.

Adhesive Failure: What is Adhesive Failure? Failure of a bonded joint between the adhesive and the substrate. Can be indicative of poor surface preparation or contamination, or incorrect adhesive selection for the substrate materials.

Adhesive: What is Adhesive? A substance used to bond materials by surface attachment.

Aerogel: What is an Aerogel? A homogeneous, low-density solid state material derived from a gel, in which the liquid: component of the gel has been replaced with a gas. The resulting material has a porous structure with an average pore size below the mean free path of air molecules at standard atmospheric: pressure and temperature.

Air-Bubble Void: What is an Air-Bubble Void? Air entrapment within and between the plies of reinforcement or within a bondline or encapsulated area; localized, non-interconnected, spherical in shape.

Aliphatic: What is Aliphatic? An organic substance containing straight or branched chain arrangements of carbon atoms.

Alkalinity: What is Alkalinity? The quality of a material to be basic or alkaline when exposed to moisture or water producing a: blue reaction to litmus paper. A pH measure greater than 7.0.

Ambient Air: What is Ambient Air? Ambient Air is generally the air surrounding an object or a surface, consisting of ambient temperature, ambient humidity, etc.

Ambient Temperature: What is Ambient Temperature? Ambient Temperature is the average temperature of the medium, usually air, surrounding the object under consideration.

Ambient: What is Ambient? Surrounding-encompassing (Generally applied to temperature, humidity and atmospheric: conditions).

Annular Space (Annulus): What is an Annular Space (Annulus)? The distance between a penetrating item and the surrounding opening.

Apparent Thermal Conductivity: What is Apparent Thermal Conductivity? A thermal conductivity assigned to a material that exhibits thermal transmission by several: modes of heat transfer resulting in property variation with specimen thickness, or surface: emittance. (See conductivity, thermal).

Apparent Thermal Resistivity: What is Apparent Thermal Resistivity? A thermal resistivity assigned to a material that exhibits thermal transmission by several modes: of heat transfer resulting in property variation with specimen thickness, or surface emittance. (See resistivity, thermal, R-value).

Appearance Covering: What is Appearance Covering? Materials used to improve the aesthetics of the finished product.

Application Temperature Limits: What are Application Temperature Limits? Minimum and maximum temperatures between which it is usually safe to service finishes, adhesives and sealants without endangering the integrity of the material. For instance, a thermoset material such as polyisocyanurate is acceptable in manufacturing processes up to 300F (350 intermittent), while a substantial percentage of composite substrates are thermo-plastics that soften above 165F.

Aramid: What is an Aramid? Aromatic polyamide fibers.

Area Weight: What is Area Weight? Weight per unit area for a specified sample, in units of lbs/ft² (kg/m²).

Aromatic: What is an Aromatic? A class of organic compounds containing a resonant, unsaturated ring of carbon atoms. Included are benzene, naphthalene, anthracene and their derivatives.

ASTM International: What is ASTM International? ASTM International provides a global forum for the development and publication of: international voluntary consensus standards for materials, products, systems, and services.

Attenuation: What is Attenuation? The limiting of sound propagation from one area to another.


Balanced Laminate: What is a Balanced Laminate? A composite laminate in which all laminate at angles other than 0° and 90° occur only in + pairs (not necessarily adjacent) and are symmetrical around the centerline.

Barcol Hardness: What is Barcol Hardness? A hardness value obtained by measuring the resistance to penetration of a sharp steel point under a spring load. The instrument, called the Barcol impressor, gives a direct reading on a 0 to 100 scale. The hardness value is often used as a measure of the degree of cure of a plastic.

Basic: What is Basic? See Alkalinity.

Batch: What is a Batch? A quantity of material formed during the same process or in one continuous process and having identical characteristics throughout. Also known as "lot." A Batch process can be characterized as the opposite of a continuous process.

Beading: What is Beading? Process of curling the edge of metal jacketing to accommodate sealing.

Bias Fabric: What is Bias Fabric? A fabric in which warp and fill fibers are at an angle to the length.

Binder: What is a Binder? The resin or cementing constituent (of a plastic compound) that holds the other components together. The agent applied to fiber mat or preforms to bond the fibers before laminating or molding.

Blackbody: What is a Blackbody? The ideal, perfect emitter and absorber of thermal radiation. It emits radiant energy at each: wavelength at the maximum rate possible as a consequence of its temperature, and absorbs all: incident radiance.

Bladder: What is a Bladder? An elastomeric lining for the containment of hydroproof or hydroburst pressurization medium in filament-wound structures.

Bleeding: What is Bleeding? The diffusion of coloring through a coating from its base or substrate (such as bleeding of asphalt: mastic through a paint top coat).

Blister: What is a Blister? Rounded elevation of the surface of a mastic resembling a blister on the human skin, usually the: entrapment of air or vapor.

Blowing Agent: What is a Blowing Agent? A substance incorporated in a mixture for the purpose of producing foam. For polyurethanes and polyisocyanurates this is usually a low boiling hydrocarbon liquid (such as pentane) or possibly carbon dioxide generated from the diisocyanate/water reaction or introduced as liquid CO2.

BOCA: What is BOCA? Building Officials and Code Administrators.

Body: What is Body? The viscosity or consistency of a mastic or coating.

Bond Strength: What is Bond Strength? Bond Strength is the force in tension, compression, cleavage or shear required to break an adhesive assembly.

Bond Strength: What is Bond Strength? Bond Strength is the force in tension, compression, cleavage or shear required to break an adhesive assembly. For insulation boards with a cladding, it is the bond between the cladding and the insulant. For pipe insulation it may be the bond between insulant segments.

Bonding Time: What is Bonding Time? Bonding Time - The time required for an adhesive to reach its optimum bonding strength.

Box Trench: What is a Box Trench? Built-up enclosure either in a shallow trench or buried underground.

Branch: What is a Branch? Distribution piping or ductwork, same as a main duct except, smaller and from or returning to the: main, serving two or more runouts.

Breaking Load: What is Breaking Load?  In some installations the composite or insulation material must "bridge" over a discontinuity in its support. The Breaking Load is the force necessary to create structural failure in a "bridging" condition. See Flexural Strength.

Breather Coating: What is a Breather Coating? A weather barrier coating designed to prevent water (rain, snow, sleet, spillage, wash water, etc.) from entering a composite or insulation system, while still allowing the escape of small quantities of water vapor resulting from heat applied to the moisture entrapped in the insulation.

British Thermal Unit (Btu): What is a British Thermal Unit? The British thermal unit (Btu or BTU) is a traditional unit of heat, defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Its counterpart in the metric system is the calorie.


C" VALUE (Thermal Conductance): What is “C" VALUE (Thermal Conductance)? A measure of the rate of heat flow for the actual thickness of a material. If the "K" of a material is known, the "C" can be determined by dividing the "K" by the thickness. The lower the "C", the higher the insulating value.

“C": What is "C"? “C” represents the thermal conductance of a material and is used to show the amount of heat (Btu's) that will pass per hour through 1 square foot of a homogeneous or non-homogeneous material or a combination of materials for the thickness or type under consideration for a difference in temperature of 1°F between the two surfaces. The average "C" value of an 8 inch hollow concrete block is 0.90.

Calorie: What is Calorie? A Calorie (Gram Calorie) is a unit of heat or energy. It is the amount of heat necessary to raise the temperature of 1 gram of water 1°C.

Canvas: What is Canvas? A plain-weave cotton fabric used for jacketing or covering.

Capillarity: What is Capillarity? The ability of a cellular, fibrous or granular material to diffuse water into its structure.

Carbon Fibers: What are Carbon Fibers? Fibers produced from pyrolytic degradation of synthetic organic fibers, polyacrylonitrile (PAN) or rayon, which contain about 92-99% carbon content and typically have modulus values up to 75 x 106 psi.

Catalyst: What is a Catalyst? A substance that causes or accelerates a chemical reaction when added to the reactants in a minor amount, and that is not consumed in the reaction.

Caulk: What is Caulk? To seal and make water and/or airtight.

Cavity: What is a Cavity? The space inside a mold in which a resin or molding compound is poured or injected. The female portion of a mold. That portion of the mold that encloses the molded article (often referred to as the die). Depending on the number of such depressions, molds are designated as single cavity or multiple cavity.

Cellular glass vs. polyiso: What is ISO-C1 polyiso versus cellular glass performance? ISO-C1 polyisocyanurate has >95% closed cells in its 2 lb/ft3 density. Cellular glass is roughly 3x heavier, higher cost, has higher compressive strength yet is very brittle, and has thermal insulation performance roughly 65% worse than polyiso.

Cellular Glass: What is Cellular Glass? Cell glass is typically made by foaming softened glass to produce many sealed bubbles, thus producing a closed-cell structure. Cellular glass can molded into board and small blocks, usually with a rather heavy density of about 7 to 10 lb per cu ft (14.4 to 16 kg per cu m).

Cellular Insulation: What is Cellular Insulation? Cellular Insulation is insulation composed of small, individual cells separated from each other. The cellular material may be glass or plastic such as polystyrene, polyurethane, polyisocyanurate or elastomeric. Cellular insulation may have “open” or “closed” cells.

Cellular Plastic Expanded: What is Expanded Cellular Plastic? Beads of plastic expanded by chemical or thermal means and bonded together chemically or thermally. Expanded Polystyrene (EPS) is an example.

Cellular Plastic Extruded: What is Extruded Cellular Plastic? Extruded plastic with cells formed by thermal or chemical means. Extruded Polystyrene (XPS) is an example.

Cellular Plastic: What is a Cellular Plastic? Plastic expanded by thermal or chemical cellular plastic could be either a thermoset or a thermoplastic.

Cellular Polyimide: What is a Cellular Polyimide? Insulation composed of the reaction product in which the bonds formed between monomers: during polymerization are essentially imide units forming a cellular structure.

Cellular Polystyrene: What is a Cellular Polystyrene? Thermoplastic rigid foam board composed principally of polymerized styrene resin processed to form a rigid foam having an open-cell structure. Expanded Polystyrene (EPS) is an example. Often used as composite substrate, insulation, or a combination thereof.

Cellular Polyurethane: What is a Cellular Polyurethane? Thermoset rigid foam composed principally of the catalyzed reaction product of polyisocyanate and polyol compounds, processed usually with fluorocarbon or hydrocarbon gas to form a rigid foam having a predominately closed-cell structure. Often used as composite substrate, insulation, or a combination thereof. Polyisocyanurate is a modified polyurethane.

Cellulosic Fiber:  What is Cellulosic Fiber? Insulation composed principally of cellulose fibers, across a wide range of densities and strengths, usually derived from paper, paperboard stock or wood, with or without binders.

Cement, Finishing: What is finishing cement? A mixture of dry fibrous or powdery materials, or both, that when mixed with water develops a plastic consistency, and when dried in place forms a relatively hard, smooth protective surface.

Cement, Insulating: What is an Insulating Cement? A mixture of dry granular, fibrous or powdery (or both) materials that when mixed with water: develops a plastic consistency, and when dried in place forms a coherent covering that affords: substantial resistance to heat transmission.

Centigrade: What is Centigrade? The Centigrade (C) temperature scale is a thermometric system in which 0 degrees denotes the freezing and 100 degrees the boiling point of pure water at standard atmospheric pressure.

Ceramic Fibers: What are Ceramic Fibers? Pure silica heated and expanded to produce fibers from which high-temperature insulation can be made. Sometimes called Refractory Ceramic Fibers.

Chalking: What is Chalking? A soft white or gray appearance on the surface of a weathered finish.

Checking: What is Checking? Openings of a coated surface characterized by the appearance of fine cracks in all directions.

Chemical Resistance: What is Chemical Resistance? The capability of a material to withstand exposure to acids, alkalis, salts and their solutions.

Chicken Wire: What is Chicken Wire? Hexagonal wire netting (poultry mesh) used as reinforcement or as a metal-mesh facing.

Clearance: What is Clearance? Clearance is the adequate space allowed for installation of insulation, or composite materials that may require thermal performance. Composites/insulants with higher R-values (lower K-factors) need less thickness to fit constrained spaces.

Closed Cell Foam: What is Closed Cell Foam? Closed Cell Foam is a material comprised predominantly of individual non-interconnecting cells, that in the context of composite materials and insulation (or a combination) yields a rigid foam board, block, or bunstock. The percent of closed cell structure, the size of the cells, the circularity of the cells, cell wall thickness and chemical makeup, and the specific gas within the cells will have a major impact on various strengths, stiffness, flexibility, and thermal conductivity.

Coating: What is a Coating? A “coating” is a liquid or semi-liquid that dries or cures to form a protective finish, suitable for application to composites or thermal insulation, or other surfaces. A coating may protect from water, moisture, solar irradiation, or certain chemicals. A mastic is a coating often applied in locations where a vapor barrier sheet wrap is not practical.

Co-bonding: What is Co-bonding? The curing together of two or more elements, of which at least one is fully cured and at least one is of which at least one is fully cured and at least one is uncured. Requires careful surface preparation of the previously Requires careful surface preparation of the previously - cured substrate. Additional adhesive may be required at interface Additional adhesive may be required at interface

Co-Cured: What is Co-Cured? Cured and simultaneously bonded to another prepared surface.

Co-Curing: What is Co-Curing? The act of curing a composite laminate and the act of curing a composite laminate and simultaneously bonding it to some other uncured material, simultaneously bonding it to some other uncured material, or to a core material such as balsa, honeycomb, or foam or to a core material such as balsa, honeycomb, or foam core.  All resins & adhesives are cured during the same essentially the same process. 

Code (Building): What is Code (Building)? A set of construction and materials standards, usually statutory. Model building codes are: adopted by each municipality from the major code organizations. The major code authorities are: BOCA, (Building Officials and Code Administrators, primarily Midwest), ICBO (International: Council of Building Code Officials, West and Indiana) and SBCCI (Southern Building Code: Congress, International, South). The local municipality or state can choose which major building: code is adopted.

Coefficient of Thermal Expansion: What is the Coefficient of Thermal Expansion? The fractional change in length of a material for each unit change in temperature.

Cohesion: What is Cohesion? The propensity of a single substance to adhere to itself. The internal attraction of molecular particles toward each other. The ability to resist partition of itself. The force holding a single substance together.

Combustible: What is Combustible? Provides enough fuel to make material capable of burning.

Compaction Resistance: What is Compaction Resistance? The property of a fibrous or loose-fill material that resists compaction under load or vibratory: conditions.

Compatible Materials: What are Compatible Materials? Two or more substances that can be mixed or used together without separating, reacting, or: adversely affecting the materials.

Composite Material Technology Advancement: Have there been any recent developments in inexpensively Priced composite materials? Yes, particularly in polyisocyanurate composite substrates that can be quickly manufactured and fabricated to virtually any sheet size, shape, or special cuts - - and can withstand higher temperatures. Their flexibility and low cost are resulting in the displacement of other composite substrates on the market that are more difficult to manufacture, come in limited sizes and shapes, and are more expensive.

Composite Materials: What kind of Composite Materials do you use?  Dyplast composite substrates use either polyisocyanurate or polystyrene materials and formulations in a range of densities and strengths.  We use a wide variety of base materials that can either be thermoset or thermoplastic. This allows us to focus on using the right material for your application, rather than just pushing the only material we happen to use.

Composite Materials-Why: Why do we use Composite Materials? A composite material consists of at least two different materials that are physically, rather than chemically, combined to achieve physical properties otherwise unachievable. Using composites rather than conventional materials such as steel also usually provides major weight savings and resultant advantages.

Composite: What is a Composite? A composite material is a material in which two or more distinct materials (substrates) are combined together to achieve physical properties different from wither substrate, yet remain uniquely identifiable in the final product. 

Compression Molding: What is Compression Molding? A technique for molding thermoset plastics in which a part is shaped by placing the fiber and resin into an open mold cavity, closing the mold, and applying heat and pressure until the material has cured or achieved its final form.

Compressive Strength: What is Compressive Strength? Ratio of compressive stress to compressive strain below the proportional limit. Theoretically equal to Young's modulus determined from tensile experiments.

Condensation: What is Condensation? Condensation is the act of water vapor turning into liquid upon contact with a cold surface.

Conditioned Air: What is Conditioned Air? Air treated to control simultaneously its temperature, humidity and cleanliness to meet the requirements of a conditioned space. (May be cool and/or heated and should be clearly defined.)

Conditioned Space: What is a Conditioned Space? Building area supplied with conditioned air that is heated or cooled to a certain temperature and may be mechanical controlled to provide a certain humidity level.

Conditioning: What is Conditioning? A material's ability to resist a force that tends to crush or buckle; maximum compressive load a specimen sustains divided by the specimen's original cross-sectional area. ALSO: Subjecting a material to a prescribed environmental and/or stress history before testing.

Conductance (Thermal) "C": What is Thermal Conductance "C"? The time rate of steady state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces. [The rate of heat flow for the actual thickness of a material].

Conductance, Air Film: What is Air Film Conductance? The time rate of heat flow from a unit area of a surface to its surroundings, induced by a unit temperature difference between the surface and the environment.

Conduction: What is Conduction (Thermal)? Thermal Conduction is the transfer of energy by virtue of a temperature difference. It is the process of heat transfer through a substance in which energy is transmitted from particle to particle without gross displacement of the particles.

Conductivity, Thermal (k-value): What is Thermal Conductivity (k-value)? The measure of heat that pass through a unit area of a homogeneous substance, through a unit: thickness, in a unit of time, for each unit temperature difference. The lower the k-value, the: higher the insulating value. Note: I-P units are Btu – in / hr – ft2 - °F and typical SI units are Watts / m - °C. Textbook definition: The time rate of steady heat flow through a unit area of a homogeneous: material induced by a unit temperature gradient in a direction perpendicular to that unit area.

Contact Adhesive: What is a Contact Adhesive? A Contact Adhesive is an adhesive that when tacky to the touch will adhere to itself instantaneously on contact.

Contact Molding: What is a Contact Molding? A molding technique in which reinforcement and resin are placed in a mold, with cure taking place at room temperature with a catalyst/promoter system or in a heated oven. No additional pressure is used.

Convection: What is Convection? Convection is the motion resulting in a fluid from the differences in density and the action of gravity. A warm-air furnace transfers heat to the rooms of the house by moving air. This transfer of heat by moving air is called Convection.

Core: What is a Core? The central component of a sandwich construction to which the sandwich faces or skins are attached; also, part of a complex mold that forms undercut parts.

Corrosion: What is Corrosion? Deterioration by chemical action such as rust on steel.

Coverage: What is Coverage? The area to be covered per unit volume of coating to obtain specified dry thickness and desired: performance.

Covering Capacity, Dry: What is Covering Capacity, Dry? The area covered to a dry thickness of 1 inch (25 mm) by 100 lb. (45.4 kg) of dry cement when mixed with the recommended amount of water, molded and dried to constant weight.

Creep: What is Creep? The dimensional change in a material under physical load over time beyond instantaneous elastic deformation.

Crimping: What is Crimping? Corrugating of the metal edge to reduce diameter or facilitate bending. Used on fitting gores to: mate with beaded edge of adjacent segment or on end caps for tanks and vessels.

Cross Laminated: What is Cross Laminated? Material laminated so that some of the layers are oriented at various angles to the other with respect to the laminate grain. A cross-ply laminate usually has plies oriented only at 0 and 90 degrees.

Cross-Linking: What is Cross-Linking? Applied to polymer molecules, the setting-up of chemical links between the molecular chains. When extensive, as in most thermosetting resins, cross-linking makes one infusible supermolecule of all the chains.

Cure Cycle: What is Cure Cycle? The time/temperature/pressure cycle used to cure.

Cure Stress: What is Cure Stress? A residual internal stress produced during the curing cycle of composite structures. Normally, these stresses originate when different components of a wet lay-up have different thermal coefficients of expansion.

Cure: What is to Cure? To change the properties of a material irreversibly by chemical reaction, i.e., moisture loss, off-gassing, condensation, ring closure, or addition. Cure may be accomplished with or without catalyst, and with or without heat.

C-Value (Thermal Conductance): What is C-Value (Thermal Conductance)? See Conductance, thermal.


Damming: What is Damming? The use of a substance to support firestopping materials until cured.

Decibel (Db): What is a Decibel? A logarithmic measure of the ratio of like power quantities as used in describing levels of sound: pressure or sound power.

Decomposition: What is Decomposition? The separating or breaking down of a substance into its component compounds or basic: elements.

De-humidification: What is De-humidification? De-humidification is the removal of water vapor from a gas and can be accomplished by physical, chemical, or thermal means.

Delamination: What is Delamination? The separation of a laminated plastic material along the plane of its layers.

Delivery: How long does composites Delivery take?  Of course the answer depends on the type of composite substrate as well as the supplier, yet Dyplast has a very large inventory, considerable capacity, and a fleet of trucks as well as alternative delivery arrangements with trains, ships, and aircraft.

Density: What is Density? Density of a material is the mass or weight per unit volume. The density of insulants is typically in the range of 1 to 10 lb/ft3.

Dew Point: What is Dew Point? The Dew Point is the temperature at which the condensation of water vapor begins for a given condition of humidity and pressure as the temperature of the water vapor is reduced. The dew point temperature corresponds to 100 percent relative humidity for a given absolute humidity at constant pressure.

Dew Point: What is Dew Point? Saturation temperature where water vapor and liquid occur simultaneously.

Dewpoint Temperature: What is Dewpoint Temperature? The temperature at which condensation of water vapor in a space begins for a given state of: humidity and pressure as the vapor temperature is reduced; the temperature corresponding to: saturation (100% relative humidity) for a given absolute humidity at constant pressure.

Diffusivity, Thermal: What is Thermal Diffusivity? The ratio of thermal conductivity of a substance to the product of its density and specific heat.

Dimensional Stability: What is Dimensional Stability? That property of a material that enables it to maintain its original size, shape and dimensions.

Dry: What is to Dry? To change the physical state of a substance by the loss of solvent constituents by evaporation, absorption, oxidation or a combination of these factors.

Dual Temperature: What is Dual Temperature? Systems of equipment that operate as cold condition and hot application.

Duct Flange (Stiffener): What is a Duct Flange? A structural or fabricated angle iron shape, attached to the exterior surfaces of a duct at specified: intervals for the purpose of reinforcing the metal and assembly of the ducts.

Duct: What is a Duct? A Duct is a passageway made of sheet metal or other suitable material used for conveying air or other gas.


Elasticity: What is Elasticity? That property of materials by virtue of which they tend to recover their original size and shape after removal of a force causing deformation.

Elastomer: What is an Elastomer? A material that at room temperature can be stretched repeatedly to at least twice its original length and, immediately upon release of the stress, return with force to its approximate original length. This definition is one criterion by which materials called plastics in commerce are distinguished from elastomers and rubbers.

Elastomeric: What is an Elastomeric? A closed-cell foam containing elastomers that provide the property of high elasticity.

Elongation: What is Elongation? Deformation caused by stretching. The fractional increase in length of a material stressed in tension. (When expressed as percentage of the original gage length, it is called percentage elongation.)

Emissivity: What is Emissivity? Emissivity is a characteristic of a surface which determines its ability to emit or give off heat by radiation. Its value is the ratio of heat radiated by a body to the heat radiated by a black body under the same conditions. Values range from 0 to 1.

Emittance, Directional: What is Directional Emittance? The ratio of the radiance from a surface in a particular direction to the radiance from a blackbody: at the same temperature under the same conditions.

Emittance, Hemispherical: What is Hemispherical Emittance? The average directional emittance over a hemispherical envelope covering a surface.

Emittance, Spectral: What is Spectral Emittance? An emittance based on the radiant energy emitted per unit wavelength interval (monochromatic: radiant energy).

Emittance, Total: What is Total Emittance? An emittance that is an integrated average over all wavelengths of radiant energy emitted.

Emittance: What is Emittance? The ratio of the radiant flux emitted by a specimen to that emitted by a blackbody at the same: temperature and under the same conditions.

Emulsion: What is an Emulsion? Insoluble fine solids or liquids dispersed in another liquid, usually water.

Epoxy Resins: What are Epoxy Resins? A two-part compound of an epoxy and catalyst that cures at ambient temperatures to form: finishes which are highly resistant to solvents and chemicals. A high bond adhesive.

EPS versus XPS: What is the difference between EPS and XPS? EPS (expanded polystyrene) and XPS (extruded polystyrene) are white, rigid, thermoplastic foams, typically manufactured in densities ranging from 0.8 -  2 pcf. As the name indicates, EPS is expanded into very large blocks. XPS is extruded, thus the billets are much smaller. XPS is generally considerably more expensive than EPS, yet the physical properties of each (at comparable densities) are actually quite similar, yet often advertised as quite different. Often the differences are due to the ASTM testing protocols and the fact that XPS may have “skins” on the surface prior to fabrication that affect, for example, water absorption. Also, whereas EPS will generally wick away any absorbed moisture, XPS does not.

Exhaust Duct: What is an Exhaust Duct? A duct carrying air from a conditioned space to an outlet outside the building.

Exotherm: What is an Exotherm? The liberation or evolution of heat during the curing of a plastic product.

Expanded Metal Lath: What is Expanded Metal Lath? See lath—expanded metal.

Expanded Polystyrene (EPS): What is Expanded Polystyrene (EPS)? Expanded Polystyrene (EPS) is the generic industry name for the white rigid material made by expanding polystyrene beads with steam and pressure to bond the beads together to form blocks or to shape molds. Expanded polystyrene, manufactured from styrene is an open-cell, thermoplastic rigid foam material often fabricated into lightweight foam products such as composite sheets, special shapes, insulation, or other products combining the physical properties or each.

Expensive Composites: Aren't composites more Expensive than metal or other plastics?  A very complex questions, yet the short answer is “No”! Yet of course the devil is on the details.  “Old Sheet Aluminum” can be as cheap as $0.35/pound. After it is fabricated into the final dimensions and profiles the costs will multiply exponentially. A cubic foot of simple, unfabricated aluminum weighs 169 pounds, and the very lowest cost of an unprocessed cubic foot billet would be $59 (and more likely $100) before any downstream production.  A polyisocyanurate (thermoset plastic) rigid foam may be under $12/ft3, even after cutting sheets to close tolerances. Even after a polyiso board is laminated with aluminum, a requisite strength versus weight ratio may be far lower cost than metal. At the other end of the spectrum, a carbon fiber sheet may cost well over $300/ft3 - - before any lamination with substrates; and may be available only in very limited dimensions, production volumes and lead-time.

Exposed Spaces: What are Exposed Spaces? Those spaces not referred to as concealed or as defined by the specifier.

Extruded Polystyrene (XPS): What is Extruded Polystyrene (XPS)? XPS is an extruded thermoplastic that soften at 165F. Since it is extruded rather than expanded the billets are somewhat small. XPS is generally considerably more expensive than Expanded Polystyrene, yet the physical properties of each (at comparable densities) are actually quite similar, yet often advertised as quite different. Often the differences are due to the ASTM testing protocols and the fact that XPS may have “skins” on the surface prior to fabrication that affect, for example, water absorption.


Fahrenheit: What is Fahrenheit? Fahrenheit (F) is a temperature scale in which 32 degrees denotes freezing and 212 degrees the boiling point of pure water at standard atmospheric pressure.

Fatigue Strength: What is Fatigue Strength? The maximum cyclical stress a material can withstand for a given number of cycles before failure occurs. The residual strength after being subjected to fatigue.

Fatigue: What is Fatigue? The failure or decay of mechanical properties after repeated applications of stress. Fatigue tests give information on the ability of a material to resist the development of cracks, which eventually bring about failure as a result of a large number of cycles.

Fiber Content: What is Fiber Content? The amount of fiber present in a composite. This is usually expressed as a percentage volume fraction or weight fraction of the composite.

Fiber GlassWhat is Fiber Glass? A synthetic vitreous fiber made by melting predominantly silica sand and other inorganic materials, and then physically forming the melt into fibers. Often used as an insulation product, there are often other materials applied to the mineral wool such as binders, oils, etc. Commonly referred to as either fiber glass or fiberglass.

Fiber-Reinforced Plastic (FRP): What is Fiber-Reinforced Plastic (FRP)? A general term for a composite that is reinforced with cloth, mat, strands, or any other fiber form.

Fibrous Glass: What is Fibrous Glass? Fibrous glass is a synthetic vitreous fiber made by melting predominantly silica sand and other inorganic materials, and then physically forming the melt into fibers. Often used as an insulation product, there are often other materials applied to the mineral wool such as binders, oils, etc. Commonly referred to as either fiber glass or fiberglass.

Filament: What is a Filament? The smallest unit of a fibrous material. The basic units formed during drawing and spinning, which are gathered into strands of fiber for use in composites. Filaments usually are of extreme length and very small diameter, usually less than 25 mm (1 mil). Normally filaments are not used individually. Some textile filaments can function as yarn when they are of sufficient strength and flexibility.

Film (Wet): What is Film (Wet)? The applied layer of mastic or coating before curing or drying.

Finish: What is Finish? Material applied to fibers, after sizing is removed, to improve matrix-to-fiber coupling.

Fire Resistance: What is Fire Resistance? Fire Resistance is the property of a material or assembly to withstand fire or give protection. It is characterized by the ability to confine a fire and to continue to perform a given structural function.

Fire Retardance (FR): What is Fire Retardance (FR)? The property of a material that retards the spread of fire.

Firestopping: What is Firestopping? Fire stopping is the furnishing and installing a material or a combination of materials to form an effective barrier against the spread of flame, smoke, gases and moisture. It is to maintain the integrity of the fire-rated construction.

Fish-Mouth: What is a Fish-Mouth? A gap between layers of sheet materials caused by warping or bunching of one or both layers.

Flame Retardant: What is a Flame Retardant? The quality of a material to limit the flame spread across its surface.

Flame Spread: What is Flame Spread? Flame spread or surface burning characteristics rating is a ranking derived by laboratory standard test methodology (e.g. ASTM E84) of a material's propensity to spread flames. The ratings are generally compared to the flame spread of red oak as a baseline.

Flame Spread: What is Flame Spread? The index rate expressed in distance and time at which a material will propagate flame on its surface.

Flash Point: What is Flash Point? The temperature at which combustion is initiated.

Flashing: What is Flashing? The arrangement of metal or other weather barrier or integrity.

Flexibility: How do you define Flexibility? That property of a material which allows it to be bent (flexed) without loss of strength.

Flexural Modulus: How do you define Flexural Modulus? Ratio of maximum fiber stress to maximum strain, within elastic limit of the stress-strain diagram obtained in the flexure test. The flexural modulus is a measure of elasticity, or the ability for the material to be deformed and return to its original shape. An alternate term is the Flexural Modulus of Elasticity.

Flexural Strength: How do you define Flexural Strength? The flexural strength of a material is its ability to resist deformation under load, or how much you can bend the material before it starts to break. For materials that do not break, the load at yield, typically measured at 5% deformation/strain of the outer surface, is reported as the flexural strength or flexural yield strength. The general term for bending stiffness is flexural rigidity, which is the product of the material's elastic modulus and the cross section moment of inertia.

Foamed Plastic: What is Foamed Plastic? Plastic expanded to a cellular form by thermal or chemical means. Extruded plastics are often considered foamed, as well.

Fracture: What is a Fracture? A rupture of the surface of a laminate because of external or internal forces, with or without complete separation.

F-Rating: What is F-Rating? A rating usually expressed in hours indicating a specific length of time that a fire resistive barrier can withstand fire before being consumed or permits the passage of flame through an opening in the assembly, as determined by ASTM E 814 (UL 1479).

Freeze/Thaw Stability: What is Freeze/Thaw Stability? The property of a product that allows it to be subjected to temperatures below freezing and still be useable when returned to room temperature.

Fresh Air Duct (Make-Up Air): What is a Freeze/Thaw Stability? A duct used to convey outdoor air to a point within the building, terminating at the mixing plenum, air handling unit or discharge grill.

FSK (Foil scrim Kraft): What is FSK (Foil scrim Kraft)? This is a laminate composed of a thin layer of aluminum foil, glass fiber reinforcing scrim, and Kraft paper.


Galvanic Corrosion (Electrolysis): What is Galvanic Corrosion (Electrolysis)? Effect of two dissimilar metals in the presence of an electrolyte to produce a weak voltaic cell: causing depleting or pitting of the more soluble metal.

Gel Coat: What is a Gel Coat? A quick setting resin applied to the surface of a mold and gelled before lay-up. The gel coat becomes an integral part of the finished laminate, and is usually used to improve surface appearance and bonding.

Gel Time: What is Gel Time? The time required for a liquid material to form a gel under specified conditions of temperature as measured by a specific test.

Gel: What is a Gel? The initial jellylike solid phase that develops during the formation of a resin from a liquid. A semisolid system consisting of a network of solid aggregates in which liquid is held.

Glass Cloth: What is Gel? Conventionally woven glass fiber material; certain lightweight glass fabrics are also called scrims.

Glass Fabric: What is Glass Fabric? Open-weave glass fiber used as a reinforcing membrane.

Glass Fiber: What is Glass Fiber? An inorganic fiber manufactured as continuous filament from molten glass or silica, normally: used for reinforcement, tissue or textiles.

Glass Scrim: What is Glass Scrim? See glass fabric.

Glass Transition Temperature (Tg): What is the Glass Transition Temperature? The approximate midpoint of the temperature range over which the glass transition takes place. The temperature at which increased molecular mobility results in significant changes in the properties of a cured resin system or other material. Also, the inflection point on a plot of modulus versus temperature. 

Graphite Fibers: What are Graphite Fibers? A group of carbon fibers which have a carbon content of about 99% and also have high modulus values. This term is used interchangeably with "carbon fibers" throughout the industry.

Graybody: What is a Graybody? A body having the same spectral emittance at all wavelengths.


Hardener: What is aa Hardener? A substance used to promote or control curing action by taking part in it; as opposed to catalyst.

Hardness: What is Hardness? The resistance to surface indentation usually measured by the depth of penetration (or arbitrary units related to the depth of penetration) of a blunt point under a given load using a particular instrument according to a prescribed procedure.

Heat Distortion Point: What is the Heat Distortion Point? The temperature at which a standard test bar deflects a specified amount under a stated load. Now called deflection temperature.

Heat Flow, Heat Flow Rate: What is the Heat Flow or Heat Flow Rate? The quantity of heat transferred to or from a system in unit time.

Heat Flux Transducer (HFT): What is a Heat Flux Transducer? A device containing a thermopile (or equivalent) that produces an output that is a function of the: heat flux.

Heat Flux: What is Heat Flux? The heat flow rate through a surface of unit area perpendicular to the direction of heat flow.

Heat Resistance: What is Heat Resistance? The property or ability of plastics and elastomers to resist the deteriorating effects of elevated temperatures.

Heat Sink: What is a Heat Sink? A contrivance for the absorption or transfer of heat away from a critical element or part. Bulk graphite is often used as a heat sink.

Heat Transmission: What is Heat Transmission? Heat Transmission is any flow of heat and usually refers to conduction, convection and radiation combined.

Hertz (Hz): What is Hertz? A measurement of sound frequency measured in cycles per second.

High Velocity Duct: What is a High Velocity Duct? A duct designed with air flow at more than 2,000 feet per minute velocity with a static pressure: exceeding 6 inches.

Homogeneous Material: What is a Homogeneous Material? A material in which relevant properties are not a function of the position within the material.

Honeycomb: What is a Honeycomb Material? Resin-impregnated material manufactured in (usually) hexagonal cells that serves as a core material in sandwich constructions. Honeycomb may also be metallic or polymer materials in a rigid, open-cell structure.

Humidity, Absolute: What is Absolute Humidity? The ratio of the mass off water vapor to total volume of an air sample. The I-P units are pounds: of moisture per pound of cubic foot of air and the SI units are grams or kilograms of moisture per: cubic meter of air.

Humidity, Ratio: What is the Ratio Humidity? The ratio of the mass of water vapor to the mass of dry air in an air sample. The I-P units are: either pounds of moisture per pound of dry air or grains of moisture per pound of dry air; the SI: units are grams of moisture per gram of dry air.

Humidity, Relative: What is Relative Humidity? One of the following ratios (a) the mole fraction of water vapor in a given moist air sample to the: mole fraction in the air sample saturated at the same temperature and pressure; (b) the vapor: pressure in a given moist air sample to the vapor pressure in the air sample saturated at the same: temperature and pressure and (c) the humidity ratio in a given moist air sample to the humidity: ratio in the air sample saturated at the same temperature and pressure. There are no units.

Humidity: What is Humidity? A measure of the amount of water vapor in the ambient air.

Humidity-Absolute: What is Humidity-Absolute? Absolute Humidity is the weight of water vapor per unit volume (lb/cu.ft.).

Humidity-Relative: What is Humidity-Relative? Relative Humidity is the ratio of the weight of water vapor in a mixture of water vapor and air to the weight of water vapor in dry saturated air at the same temperature. The ratio is usually expressed as a percent of relative humidity.

Humidity-Specific: What is Specific Humidity? Specific Humidity is the weight of water vapor per pound of dry air in a mixture of water vapor and air.

Hybrid Composite: What is a Hybrid Composite? A composite laminate comprised of laminae of two or more composite material systems, e.g., glass and carbon. It also applies to woven fabrics having more than one type of fiber.

Hygroscopy: What is Hygroscopy? Tendency of a material to absorb water vapor from the air. Especially pertinent for materials whose physical characteristics are altered by effects of water vapor.


IARC: What is the IARC? International Agency for Research on Cancer

ICBO: What is the ICBO? International Council of Building Code Officials.

ICC: What is the ICC? International Code Council.

Impact Resistance: What is Impact Resistance? Capability of a material and/or finish to withstand mechanical or physical abuse.

Impact Strength: What is Impact Strength? A material's ability to withstand shock loading as measured by the work done in fracturing a specimen

Impale: What is to Impale? To pierce or fix by piercing on a sharp point or pin.

Impregnate: What is to Impregnate? To saturate the voids and interstices of a reinforcement with a resin.

IMPs Installation: How are IMPs installed? Insulated Metal Panels (IMPs) generally consist of a metal sheet laminated/adhered to an insulant such as polyisocyanurate or polystyrene. The installation may vary from a large refrigerated warehouse to a much small sharp-freezer application where the quality of the IMP and the precision/methodology of the installation is more challenging. Consult your engineer for installation guides for the specific application.

IMPs Manufacture: Where are IMPs manufactured?  Insulated Metal Panels are manufactured at dozens of facilities across North America, yet the insulants, laminates, the quality, and the size can vary considerably. Internet searches of local suppliers and evaluation of each is warranted. For instance. displays over 16, 000 results when searching for Insulated Metal Panels

Injection Molding: What is Injection Molding? Method of forming a plastic to the desired shape by forcing heat-softened plastic into a relatively cool cavity under pressure.

Insulate: What is to Insulate? To cover with a material of low thermal conductivity in order to reduce the passage or leakage: of heat.

Insulated Metal Panel: What is an Insulated Metal Panel (IMP)? In either case, an Insulated Metal Panel consists either of a rigid insulant (such as polyiso or polystyrene) laminated to a structural metal sheet(s) or a liquid insulant (such as pour-in-place polyurethane) is poured between two metal sheets, the result of which is structural.

Insulated Metal Panel Manufacturers: Who manufactures Insulated Metal Panels (IMPs)? IMPs manufactured?  Insulated Metal Panels are manufactured at dozens of facilities across North America, yet the insulants, laminates, the quality, and the size can vary considerably.

Insulated Panel: What is an Insulated Panel? The term most generically applies to a panel of rigid sheet insulation that is sufficiently structural to “stand on its own” (such as polyisocyanurate or polystyrene), rather than for instance a batt of insulation fibers that must be adhered to a wall. More general the term applies to either a Structural Insulated Panel (SIP), or an Insulated Metal Panel (IMP). In either case, the rigid insulant is either laminated to a structural sheet (wood or metal) or a liquid insulant is poured between two structural sheets.

Insulating Cement: What is Insulating Cement? A mixture of various insulating fibers and binders with water to form a moldable paste insulation for application to fittings, irregular surfaces or voids.

Insulation: What is Insulation? Those materials or combination of materials that retard the flow of heat.

Interface: What is an Interface? The boundary or surface between two different, physically distinguishable media. On fibers, the contact area between fibers and sizing or finish. In a laminate, the contact area between the reinforcement and the laminating resin.

Interlaminar Shear: What is ab Interlaminar Shear? A shearing force tending to produce a relative displacement between two laminae along the plane of their interface.

Interlaminar: What is Interlaminar? Existing or occurring between two or more adjacent laminae.

Intumescent: What is Intumescent? A characteristic of certain firestop products that when exposed to heat, expand to seal and fill: any void in the penetration. When exposed to fire, intumescent products will form a hard char.

Isocyanate: What is Isocyanate? A compound containing the isocyanate group, -N=C=O, attached to an organic radical or hydrogen.

Isotropic: What is Isotropic? Having uniform properties in all directions. The measured properties of an isotropic material are independent of the axis of testing.



Kelvin: What is Kelvin? Kelvin (K) is a temperature scale sometimes called centigrade absolute. Its zero is at the lowest attainable temperature or 273.15° below the zero on the centigrade scale.

k-factor: What is “k-factor”? Thermal conductivity (k) is the amount of heat (Btu's) transferred in 1 hour through 1 square foot of a homogeneous material 1 inch thick for a difference in temperature of 1°F. For example, the average "k" for Armaflex is 0.25. This means that for a 1 inch thickness, there is a heat transfer of 0.25 Btu per hour per square foot for each degree difference in temperature between its two surfaces. Usually expressed in Btu/hr, sq.ft.(F/in.) in the insulation field.


Laminate (n.): What is a Laminate? A product made by bonding together two or more layers of material or materials.

Laminate (v.): How do you Laminate? By bonding together two or more layers of material(s).

Laminate Orientation: What is Laminate Orientation? The configuration of a cross-plied composite laminate with regard to the angles of cross-plying, the number of laminae at each angle, and the exact sequence of the lamina lay-up.

Laminating: What is Laminating? Laying up with resin and reinforcing fabric on virtually any surface.

LISTING (UL): What is a LISTING with Underwriters Laboratories? The UL permits the use of its listing mark (the UL mark) as its stamp of approval on goods and materials after standardized and stringent testing. Thereafter its inspectors regularly visit the producer to audit compliance with its certification requirements.

Loads on Adhesive Bonded Joints: What are the Loads on Adhesive Bonded Joints? Loads include Tension, Compression, Shear, Cleavage, Peal.

Lot: What is a Lot? A specific amount of material produced at one time using the same process and the same conditions of manufacture, and offered for sale as a unit quantity.


Manufacturing: How long is the Manufacturing and delivery process? Of course the answer depends on the type of composite substrate as well as the supplier, yet Dyplast has a very large inventory, considerable production capacity, and a fleet of trucks as well as alternative delivery arrangements with trains, ships, and aircraft.

Mat: What is a Mat? A fibrous reinforcing material comprised of chopped filaments (for chopped-strand mat) or swirled filaments (for continuous-strand mat) with a binder to maintain form; available in blankets of various widths, weights, and lengths.

Matrix: What is a Matrix? A material in which the fiber of a composite is imbedded; it can be plastic, metal, ceramic, or glass.

MDI: What is MDI? An abbreviation for 4,4’ diphenylmethane diisocyanate.

Mean Specific Heat: What is Mean Specific Heat? The quantity of heat required to change the temperature of a unit mass of a substance one degree, measured as the average quantity over the temperature range specified. (It is distinguished from: true specific heat by being an average rather than a point value).

Mean Temperature: What is Mean Temperature? Mean Temperature is the arithmetic mean of inner and outer surface temperatures of a material.

Membrane Reinforcement: What is Membrane Reinforcement? Woven or non-woven fabrics used for saturation and embedment in mastic and coating: applications to provide strength, continuity and impact resistance. See glass fabric.

Metal Bonding: What is Metal Bonding? The same as Secondary Bonding except with metal substrates instead of cured except with metal substrates instead of cured composite substrates. Sometimes metals are bonded directly to composites using one or more processes using one or more processes. Metals require very stringent surface preparation including application of corrosion inhibiting primer prior to bonding to obtain long term bond-durability at the metallic interface. Care must be taken when bonding metal to carbon as galvanic corrosion can occur in the metal substrate. 

Metric Perm: What is a Metric Perm? Perm measured at 23C Kilogram per Pascal Second square meter [kg/Pa-s-m2]

Mil: What is a Mil? The unit used in measuring the diameter of glass fiber strands, wire, and so forth (1 mil = 0.001 in.).

Modulus: What is Modulus? A measure of the ratio of load (stress) applied to the resultant deformation of a material, such as elasticity or shear.

Moisture Content: What is Moisture Content? The amount of moisture in a material determined under prescribed conditions and expressed as a percentage of the mass of the moist specimen, that is, the mass of the dry substance plus the moisture present.

Mold and Mildew Resistance: What is Mold and Mildew Resistance? Mold and Mildew Resistance is the property of a material that enables it to resist the formation of fungus growth.

Mold Pressure: What is Mold Pressure? The pressure applied to the ram of an injection machine or compression or transfer press to force the softened plastic to fill the mold cavities completely.

Mold Surface: What is Mold Surface? The side of a laminate that faced the mold (tool) during cure in an autoclave or hydroclave.

Mold (v.): How do you Mold your products?  Importantly, Dyplast does not “mold” its composite materials. Polyiso is manufactured from a complex liquid formulation that “rises” (expands) when poured onto a continuously moving belt - - resulting in a large “bun” that can be cut or fabricated into virtually any shape/size to very precise dimensions. Many of our processes are proprietary, such as tool design, chemical formulation, material dispensing and curing, and thus we can avoid the often more expensive molding processes such as: Injection Molding, Compression Molding, Rotational Molding, RTM, Liquid Injection Molding, Rubber Injection Molding, Spin Casting, Hand Lay-Up, Hand Casting, and High-Volume Meter Mix Dispensing.

Mold (n.): What is a Mold? The cavity or matrix into which, or on which, the plastic composition is placed and from which it takes form. To shape plastic parts or finished articles by heat and pressure. The assembly of all the parts that function collectively in the molding process.

Molding: What is Molding? Constructing a part within a mold. Sometimes used to denote the finished part.

Mold-Release Agent: What is a Mold-Release Agent? A lubricant, liquid, or powder (often silicone oils and waxes), used to prevent sticking of molded articles in the cavity.


NFPA: What is NFPA? National Fire Protection Association.

Noise Reduction Coefficient (NRC): What is a Noise Reduction Coefficient? A single number rating that is the arithmetic average of the individual sound absorption: coefficients at 250, 500, 1000 and 2000 Hz to the nearest 0.05.

Nominal Value: What is a Nominal Value? A value assigned for the purpose of a convenient designation. A nominal value exists in name only. It is often an average number with a tolerance so as to fit together with adjacent parts.

Noncombustible: What is Noncombustible? Noncombustible applies to a material that will not contribute fuel or heat to support a fire to which it is exposed.

Nondestructive Testing (NDT): What is Nondestructive Testing? Broadly considered synonymous with nondestructive inspection (NDI).

Nonflammable: What is Nonflammable? Nonflammable applies to a material that will release very little heat when exposed to fire or flame.

Nonflammable: What is Nonflammable? A material that will release very little heat when exposed to fire or flame.


Octave Band: What is an Octave Band? A frequency band with an upper frequency limit equal to twice the lower limit.

Open Cell Foam: What is an Open Cell Foam? Open cell foam is full of cells that aren’t completely encapsulated. In other words, the cells are deliberately left open to achieve a particular physical characteristic. For instance, to make the foam a softer, more flexible material. Open cells in a Closed Cell Foam are considered a drawback


Perm: What is a Perm? A Perm is a measure of vapor transmission rate. Defined as 1 grain of water vapor per hour for 1 square foot area for 1 inch of mercury-pressure difference. Other units are also used to express vapor transmission rates. Grains/hr., sq.ft., in.Hg.

Permeability: What is Permeability? Permeability is a rating of a material giving the amount of water vapor that passes through 1 inch thickness of the material. Grains/hr., sq.ft. (in.Hg/in.). Permeability is measured in Perm inches.

Permeance (Perms): What is Permeance? The ratio of water vapor flow to the vapor pressure difference between the two surfaces of a sheet of material (or the assembly between parallel surfaces). Permeance is measured in Perms.

pH: What is pH? A measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions, increasing with increasing alkalinity and decreasing with increasing acidity (potential of hydrogen).

Pinhole: What is a Pinhole? Very small hole through a mastic or coating.

Ply: What is a Ply? In general, fabrics or felts consisting of one or more layers (laminates, for example). The layers that make up a stack. Yarn resulting from twisting operations (three-ply yarn, for example). A single layer of prepreg. A single pass in filament winding (two plies forming one layer).

Pointing: What is Pointing? Applying or shaping cements or mastic with a small pointed trowel.

Polyethylene: What is Polyethylene? Polyethylene is a closed-cell, thermoplastic material used for insulation or composites.

Polyimide: What is a Polyimide? See cellular polyimide.

Polyisocyanurate manufacture: How is Polyiso manufactured for composite applications? When manufacturing Polyisocyanurate bunstock the primary chemical ingredients include methylene diphenyl diisocyanate (MDI) and polyols, plus blowing agents, catalysts, and fire retardants. The liquid combination flows onto a continuously moving belt, and over a period of 1-3 minutes rises (expands) and solidifies into the final bunstock, which can then be cut into virtually any length.

Polyisocyanurate Look/Feel: What does Polyisocyanurate (polyiso) insulation look and feel like? Polyisocyanurate (polyiso or PIR) is a rigid foam thermoset “plastic” that is generally tan in color and its texture is somewhat like fine sandpaper surface on a rigid foam.

Polyisocyanurate: What is Polyisocyanurate (polyiso)? Polyisocyanurate (a modified polyurethane) is a rigid closed cell thermoset foam with physical properties making it ideal for many composite applications. Added value includes, light weight, high-strength, large sizing, concise dimensional fabrication, tolerance for higher temperatures than thermoplastics, high-capacity manufacture, and more.

Polymer: What is a Polymer? A long chain molecule resulting from the chemical attachment of short molecules (monomers) of: the same product. For example, when ethylene (a gas) is polymerized, the synthetic resin: polyethylene is produced.

Polymerization: What is Polymerization? A chemical reaction in which the molecules of monomers are linked together to form polymers.

Polyol: What is a Polyol? An organic compound having more than one hydroxyl (-OH) group per molecule. In the cellular plastics industry, the term includes monomeric and polymeric compounds containing alcoholic hydroxyl groups such as polyethers, glycols, glycerol, and polyesters, used as reactants in polyurethane foam.

Polystyrene: What is Polystyrene? Polystyrene is a versatile plastic used to make a wide variety of consumer products. In the context of composite applications and insulation (or composites benefiting from thermal performance) polystyrene is a foam material, called expanded polystyrene (EPS) or extruded polystyrene (XPS), which is valued for its insulating, cushioning, and strength properties at low cost.

Polyurethane: What is a Polyurethane? Polymeric substance containing many urethane linkages. Abbreviated as PUR or PIR, depending on whether there is a greater proportion of polyol or isocyanate. [Rigid foam polyurethanes with higher isocyanate indexes are referred to as PIR, or polyisocyanurate foam]. Polyurethanes actually include a very large family of polymers with widely ranging properties and uses, all based on the reaction product of an organic diisocyanate with compounds containing a hydroxyl group, and having the 'RNHCOOR’- group in their chains. The types and properties of polyurethanes are so varied that they have been dubbed the "erector set" of the plastics industry. They may be thermosetting or thermoplastic, rigid and hard or flexible and soft, solid or cellular; and the properties of any of these types may be varied within wide limits to suit the desired application. See Polyisocyanurate.

Polyvinyl Chloride (PVC): What is a Polyvinyl Chloride? A polymerized vinyl compound using chloride.

Polyvinyl Fluoride (PVF): What is a Polyvinyl Fluoride? A polymerized vinyl compound using fluoride.

Post Cure: What is Post Cure? The exposure of certain resins to higher than normal curing temperatures after the initial cure cycle. This second stage is necessary to attain the complete cure and desired mechanical properties of the resins involved. The higher temperatures are used separately because they would result in an excessive reaction if applied throughout the entire cure.

Potential Heat: What is Potential Heat? Potential Heat is the approximate amount of Btu's required to fully burn or incinerate 1 lb. Armaflex -- 9,000 Btu's for 4.5 lb. of Armaflex.

Pressure Sensitive Tape: What is Pressure Sensitive Tape? A tape with adhesive pre-applied.

Price of board foot: What is the Price of a board foot?

Price of composites: What is the Price of polyiso versus other composites?

Price of an IMP: What is the Price of an IMP? The price of an IMP (insulated metal panel) varies considerable based on the insulant material (e.g. polyiso versus EPS), the metal skin (e.g. stainless versus PVC), the size and thickness, and the quality of the assembly.

Price of polyiso: What is the Price of polyisocyanurate? The price of polyisocyanurate is generally quoted in cents per board foot, and varies with density. For 2 lb/ft3 polyiso rigid foam, the price can be well under a $1.00/board foot.

Price of a SIP: What is the Price of a SIP? The price of a SIP (structural insulated panel) varies considerable based on the insulant material (e.g. polyiso versus EPS), the skin (e.g. wood versus steel), the size and thickness, and the quality of the assembly.

Primer: What is a Primer? A coating applied to a surface, before the application of an adhesive, lacquer, enamel, and so forth, to improve the adhesion performance or load-carrying ability of the bond.

Processing Window: What is the Processing Window? The range of processing conditions, such as stock (melt) temperature, pressure, shear rate, and so on, within which a particular grade of plastic can be fabricated with optimum or acceptable properties by a particular fabricating process.

Project Management: Who manages my Project at Dyplast?  We will assign a project engineer to your project who will be responsible for managing every aspect of the project, from identifying performance requirements to producing prototypes to delivering the first articles for production. Generally, your globe composite project engineer will interface directly with your program manager, engineer, or user representative to make sure we understand the requirements of the project and ultimately deliver the best parts for the application.

Project Tracking: How do you keep track of my Project?  Dyplast composite manages anywhere between 75 to 100 projects at any given time. We understand how important it is that your project gets the attention it deserves. That's why every project is maintained on our customized workflow management system, giving us up-to-the-minute information on project status, deliverables, and costs.

Puncture Resistance: What is Puncture Resistance? That property of a material that enables it to resist punctures or perforations under blows or: pressure from sharp objects.



Radiance: What is Radiance? The rate of radiant emission per unit solid angle and per unit projected area of a source in a: stated angular direction from the surface (usually the normal).

Radiant Flux Density: What is Radiant Flux Density? The rate of radiant energy emitted from unit area of a surface in all radial directions of the: overspreading hemisphere.

Radiant Heat: What is Radiant Heat? Heat radiating from a heated body, as distinguished from that transmitted by an intervening body.

Radiation: What is Radiation? Thermal Radiation is the transmission of energy by means of electromagnetic waves. Radiated heat moves at high speed through the air without heating the air and flows in direct lines from a warm surface to a cooler one. Sun heat is radiated heat.

Rankine: What is Rankine? The Rankine (R) temperature scale is sometimes called Fahrenheit absolute. Its zero is at the lowest attainable temperature or 459.67 (460) degrees below the zero on the Fahrenheit scale.

Reflectance: What is Reflectance? The fraction of the incident radiation upon a surface that is reflected from the surface.

Reflectivity: What is Reflectivity? Reflectivity is the fraction of the incident radiation reflected by a surface. (No radiant heat is reflected by a perfect black body.) With an opaque non-black body: Emissivity = Absorptivity = 1 – Reflectivity

Refractory Materials: What are Refractory Materials? Materials, usually fibers, that do not significantly deform or change chemically at very high: temperatures. Manufactured in blanket, block, brick or cement form.

Reinforcement: What is Reinforcement? A material added to the matrix to provide the required properties; ranges from short fibers through complex textile forms.

Reinforcing Cloth or Fabric: What is Reinforcing Cloth or Fabric? A woven cloth or fabric of glass or resilient fibers used as reinforcement to a mastic.

Relative Humidity: What is Relative Humidity? One of the following ratios (a) the mole fraction of water vapor in a given moist air sample to the: mole fraction in the air sample saturated at the same temperature and pressure; (b) the vapor: pressure in a given moist air sample to the vapor pressure in the air sample saturated at the same: temperature and pressure and (c) the humidity ratio in a given moist air sample to the humidity: ratio in the air sample saturated at the same temperature and pressure. There are no units.

Release Agents: What are Release Agents? Materials that are used to prevent cured matrix material from bonding to tooling.

Release Film: What is a Release Film? An impermeable layer of film that does not bond to the resin being cured. See also separator.

Resiliency: What is Resiliency? The property of a material that enables it to recover its original shape and thickness after compression.

Resin Content: What is Resin Content? The amount of resin in a laminate expressed as either a percentage of total weight or total volume.

Resin: What is a Resin? A material, generally a polymer, that has an indefinite and often high molecular weight and softening/melting range, and exhibits a tendency to flow when it is subjected to stress. Resins are used as the matrices to bind together the reinforcement material in composites.

Resistance to Acids, Caustics, and Solvents: Define Resistance to Acids, Caustics, and Solvents? The ability of a material to resist decomposition by various acids, caustics and solvents to which: it may be subjected.

Resistance to Air Erosion: Define Resistance to Air Erosion? The ability of a material to resist erosion by air currents over its surface.

Resistance to fungal or bacterial growth: What is Resistance to fungal or bacterial growth? Is necessary in food or cosmetic process areas.

Resistance to ultraviolet light: Why consider Resistance to ultraviolet light? Significant if application is outdoors.

Resistance, Abrasion: What is Abrasion Resistance? The ability to withstand scuffing, scratching, rubbing or wind-scouring.

Resistance, Freeze-Thaw: What is Freeze-Thaw Resistance? Resistance to cycles of freezing and thawing that could affect application, appearance or: performance.

Resistance, Impact (Toughness): What is Impact Resistance? Ability to withstand mechanical blows or shock without damage seriously affecting the: effectiveness of the material or system.

Resistance, Thermal (R-value): What is Thermal Resistance? A measure of the ability to retard heat flow rather than the ability to transmit heat. R-value is the: numerical reciprocal of “U” or “C,” thus R = 1/U or 1/C. Thermal resistance R-value is used in: combination with numerals to designate thermal resistance values: R-11 equals 11 resistance: units. The higher the “R,” the higher the insulating value. The I-P units are °F – ft2 – hr / Btu; the: SI units are °C – m2 / W.

Resistivity, Thermal (r): What is Thermal Resistivity? The quantity determined by the temperature difference, at steady state, between two defined: parallel surfaces of a homogeneous material of unit thickness, that induces a unit heat flow rate: through a unit area. (r in SI units: m K/W.) (r in inch-pound units: h ft F/Btu or, h ft ² F/Btu in.).

Return Air Duct: What is a Return Air Duct? A duct carrying air from a conditioned space to the mixing air duct or plenum unit.

Rigidity: What is Rigidity? The property of a material that opposes any tendency for it to bend (flex) under load.

Riser: What is a Riser? The vertical portion of a main, branch or runout.

R-Value (Thermal Resistance): What is R-Value? See Resistance, thermal.


Sample: What is a Sample? A group of items, observations, test results, or portions of material, taken from a large collection: of items, observations, test results, or quantities of material, which serves to provide information: that may be used as a basis for making a decision concerning the larger collection.

Sandwich Construction: What is Sandwich Construction? A composite composed of lightweight core material (usually honeycomb or foamed plastic) to which two relatively thin, dense, high-strength, functional, or decorative skins (also called faces) are adhered.

Saturation: What is Saturation? Saturation is the condition of co-existence in stable equilibrium of a vapor and a liquid or a vapor and a solid of the same substance.

SBCCI: What is SBCCI? Southern Building Code Congress, International.

Scrim: What is Scrim? A low-cost reinforcing fabric made from continuous filament yarn in an open-mesh construction. Used in the processing of tape or other B-stage material to facilitate handling. Also used as a carrier of adhesive, to be used in secondary bonding.

Seal: What is to Seal? To make water-tight or airtight.

Sealer: What is a Sealer? A liquid coating used to prevent excessive absorption of finish coats into porous surfaces.

Secondary Bonding: What is Secondary Bonding? The joining together, by the process of adhesive bonding, two or more pre-cured composite parts, during which the only chemical or thermal reaction occurring is the curing chemical or thermal reaction occurring is the curing of the adhesive itself of the adhesive itself. Requires careful preparation of each previously cured substrate at the bonding surfaces substrate at the bonding surfaces. Usually requires well designed fixturing to align & clamp parts during processing parts during processing. Re-heating previously cured substrates can be risky.

Self-Extinguishing: What is Self-Extinguishing? Self-extinguishing is the property of a material that enables it to stop its own ignition after external ignition sources are removed.

Separator: What is a Separator? A permeable layer that also acts as a release film. Porous Teflon®-coated fiberglass is an example. Often placed between lay-up and bleeder to facilitate bleeder system removal from laminate after cure.

Service Temperature Limits: What is the Service Temperature Limit? The temperature to which the material may be subjected during continuous operation or intermittent exposure.

Set Up: What is to Set Up? To harden, as in curing of a polymer resin.

Sharp freezer: What is a Sharp freezer? In cold-storage practice, a freezer room generally operating at -10°F or lower.

Shear Modulus: What is Shear Modulus? Shear modulus, sometimes referred to as the modulus of rigidity, is defined as the ratio of shear stress to the shear strain. Shear modulus is usually measured in ksi (kips per square inch) or GPa (gigapascals). 

Shear Strength: What is Shear Strength? The maximum shear stress that a material is capable of sustaining. Shear strength is calculated from the maximum load during a shear or torsion test and is based on the original cross-sectional area of the specimen.

Shelf Life: What is Shelf Life? The length of time a material, substance, product, or reagent can be stored under specified environmental conditions and continue to meet all applicable specification requirements and/or remain suitable for its intended function.

Shipping: How long does it take to Ship composites?  Of course the answer depends on the type of composite substrate as well as the supplier, yet Dyplast has a very large inventory, considerable production capacity, and a fleet of trucks as well as alternative delivery arrangements with trains, ships, and aircraft.

Shrinkage: What is Shrinkage? The relative change in dimension from the length measured on the mold when it is cold to the length of the molded object 24 hours after it has been taken out of the mold.

Size: What is to Size? Any treatment consisting of starch, gelatin, oil, wax, or other suitable ingredient applied to yarn or fibers at the time of formation to protect the surface and aid the process of handling and fabrication or to control the fiber characteristics. The treatment contains ingredients that provide surface lubricity and binding action but, unlike a finish, contains no coupling agent. Before final fabrication into a composite, the size is usually removed by heat cleaning, and a finish is applied.

Skin: What is a Skin? A layer of relatively dense material used in a sandwich construction of the surface of the core.

Smoke Density: What is Smoke Density? The amount of smoke given off by the burning material compared to the amount of smoke given: off by the burning of a standard material.

Smoke Development: What is Smoke Development? Smoke Development is the characteristic of a material to emit smoke when exposed to flame or fire. Building codes generally require a smoke development rating of 50 or less, as measured per ASTM E84. Other codes require a rating of 450 or less, which meets Class 1 requirements. Smoke development can also be measured per UL723.

Soaking Heat: What is Soaking Heat?  A test condition in which the specimen is completely immersed in an atmosphere maintained at a: controlled temperature.

Solar Resistance What is Solar Resistance? Solar Resistance is the property of a material to resist decomposition by the ultraviolet rays from the sun or the passage of radiant heat from the sun.

Solids Content: What is Solids Content? The percentage of the non-volatile matter in adhesives, coatings or sealants. It may be based on: weight or volume.

Solvent: What is a Solvent? Any substance, usually a liquid, that dissolves another substance.

Sound Absorption Coefficient (SAC): What is Sound Absorption Coefficient? The percentage of sound energy incident on the surface of a material that is absorbed by the: material.

Sound Transmission Class (STC): What is Sound Transmission Class? A single number rating based on sound transmission loss measurements of a partition between: adjacent closed rooms.

Sound Transmission Loss (STL): What is Sound Transmission Loss? The reduction in level measured in decibels as sound energy passes through a material or: composite construction.

Specific Gravity: What is Specific Gravity? The density (mass per unit volume) of a material divided by that of water at a standard temperature.

Specific Heat What is Specific Heat? Specific Heat is the heat absorbed (or given up) by a unit mass of a substance when its temperature is increased (or decreased) by 1 degree. Or the ratio of the amount of heat required to raise unit mass of a material 1 degree to that required to raise unit mass of water 1 degree at some specified temperature.

Standard Deviation: What is a Standard Deviation? A measure of dispersion of data from the average. The root means square of the individual deviation from the average.

Steady State (Thermal): What is Thermal Steady State? A condition for which all relevant parameters in a region do not vary over two consecutive steady-state time periods by more than the steady-state tolerance, and no long-term monotonic: drifts are present. Where, the steady-state time period is the time constant of the apparatus specimen system with additional time necessary if physical phenomena are present, such as moisture transport, which could cause a long-term monotonic drift.

Stiffener (Duct Flange): What is a Duct Flange Stiffener? A structural or fabricated angle iron shape, attached to the exterior surfaces of a duct or bulkhead: at specified intervals for the purpose of reinforcing the metal and to prevent vibration.

Stiffness: What is Stiffness? A measure of modulus. The relationship of load and deformation. The ratio between the applied stress and resulting strain. A term often used when the relationship of stress to strain does not conform to the definition of Young's modulus.

Strand: What is a Strand? Normally an untwisted bundle or assembly of continuous filaments used as a unit, including slivers, tows, ends, and yarn, for example. Sometimes a single fiber or filament is called a strand.

Strength, Transverse (or Flexural): What is Transverse (or Flexural) Strength? The breaking load applied normal to the neutral axis of a beam.

Structural Adhesive: What is Structural Adhesive? Adhesive used for transferring required loads between adherends exposed to service environments typical for the structure involved.

Structural Bond: What is a Structural Bond? A bond that joins basic load-bearing parts of an assembly. The load may be either static or dynamic.

Structural Insulated Panel Manufacturers: Who manufactures Structural Insulated Panels (SIPs)? An internet search of the keyphrase results in dozens of returns.

Structural Insulated Panel Load: How much load could a Structural Insulated Panel take? The strengths of a SIP generally depend on the external material (wood or metal), the type of insulant, and the thickness.

Structural Insulated Panel Definition: What is a Structural Insulated Panel (SIP)? A structural insulated panel, or structural insulating panel, (SIP), is a form of sandwich panel used in the construction industry. It is structural to the extent the SIP can form the wall of a 1-2 story building without or with minimal additional wood or metal studs. The exterior of the SIP is generally either wood (e.g. OSB or plywood) or metal. The insulation is typically expanded polystyrene or polyisocyanurate.

Substrate (within the context of composites): What is a Substrate? Sometimes referred to as the "base" layer in a composite structure, yet often any structural component of a composite may be referred to as a substrate; infrequently, the finished composite product may itself be referred to as a substrate.

Supply Air Duct: What is a Supply Air Duct? A duct that carries conditioned air from air supply units to room diffusers or grilles.

Surface Conductance: What is Surface Conductance? Surface Conductance (h) is the amount of heat transmitted by radiation, conduction, and convection from a surface to the fluid surrounding it, or vice versa, in one hour for each square foot for a temperature difference of 1 degree between the surface and the fluid. Usually expressed as Btu/hr., sq.ft., F.


Tack: What is Tack? The property of an adhesive that enables it to form a measurable bond immediately after: adhesive and adherent are brought into contact under low pressure.

Tear Strength: What is Tear Strength? The property of a material that enables it to resist being pulled apart by opposing forces.

Temperature Dry-bulb: What is Temperature Dry-bulb? Dry-bulb Temperature is sometimes called ambient or sensible temperature and it is the temperature of a gas or mixture of gases as measured by a transducer that remains dry. The transducer may be a thermometer, thermocouple, resistance bulb or any other temperature measuring device. To be truly accurate, it should be shielded from radiation or corrected for it.

Temperature Limits: The upper and lower temperatures at which a material will experience no change in its physical: properties.

Temperature Wet-bulb: What is Temperature Wet-bulb? Wet-bulb Temperature is the temperature indicated by a wet-bulb transducer when used according to accepted standards. Technically, the thermodynamic wet-bulb temperature is the temperature at which liquid or solid water, by evaporating into air, can bring the air to saturation adiabatically at the same temperature.

Temperature: What is Temperature? Temperature is the thermal state of matter as regards its tendency to communicate heat to matter in contact with it. If there is no difference in temperature, no heat will flow on contact.

Template: What is a Template? A pattern used as a guide for cutting and laying plies, or vapor barrier sheets.

Tensile Strength: What is Tensile Strength? The maximum load or force per unit cross-sectional area, within the gage length, of the specimen. The pulling stress required to break a given specimen.

Test Specimen: What is a Test Specimen? The portion of a test unit needed to obtain a single test determination.

Thermal Capacity: What is Thermal Capacity? The quantity of heat required to change the temperature of the body one degree. For a: homogeneous body, it is the product of mass and specific heat. For a nonhomogeneous body, it is: the sum of the products of mass and specific heat of the individual constituents. (May also be: seen as heat capacity.)

Thermal Conductivity: What is Thermal Conductivity? The ability of a material to conduct heat.

Thermoplastic: What is a Thermoplastic? Capable of being repeatedly softened by an increase of temperature and hardened by an increase in temperature. Applicable to those materials whose change upon heating is substantially physical rather than chemical and that in the softened stage can be shaped by flow into articles by molding or extrusion.

Thermoset: What is a Thermoset? A plastic that, when cured by application of heat or chemical means, changes into a substantially infusible and insoluble material.

Thixotropy: What is Thixotropy? The tendency of a material to cling to a vertical surface.

Thread Count: What is Thread Count? The number of yarns (threads) per inch in either the lengthwise (warp) or crosswise (fill or weft) direction of woven fabrics.

Toxicity: What is Toxicity? Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Must be particularly considered in food processing plants and potential fire hazard areas.

Transmission, Heat: What is Heat Transmission? The quantity of heat flowing through unit area due to all modes of heat transfer induced by the: prevailing conditions.

Transmittance, Thermal (U-value): What is Thermal Transmittance (U-value)? The combined thermal value of all the materials in an insulation system, air spaces, and surface air: films. The heat transmission in unit time through unit area of a material or construction and: boundary air films, induced by unit temperature difference between the environments on each: side. The I-P units are Btu / (hr – sq ft – deg F temperature difference) and the SI units are W /: (sq m – deg C temperature difference). Note: This heat transmission rate has been called the: overall coefficient of heat transfer.

T-Rating: What is the T-Rating? A rating usually expressed in hours indicating the length of time that the temperature on the nonfire side of a fire-rated assembly exceeds 325°F above its ambient temperature as determined by: ASTM E-814 (UL-1479).


“U": What is "U"? “U” designates the total or overall transmission of heat (Btu's) in 1 hour per square foot of area for a difference in temperature of 1°F between the air on one side to air on the other side of a structure.

UL: Underwriters Laboratories: What is the Underwriters Laboratories (UL)?  An independent materials testing company. UL provides testing, evaluation, and listing services for products having specific safety-related features. UL test standards generally are similar to ASTM International standards when both exist.

Ultrasonic Testing: What is Ultrasonic Testing? A nondestructive test applied to materials for the purpose of locating internal flaws or structural discontinuities by the use of high-frequency reflection or attenuation (ultrasonic beam).

Ultraviolet Light: What is Ultraviolet Light resistance? Resistance to ultraviolet light is significant if application is outdoors.

Urethane: What is a Urethane? Plastic foam of rigid polyurethane closed-cell rigid foam thermoset plastic. Urethanes are used in a wide array of applications, including as insulation in boards, pipe insulation, foamed-in-place, or composite substrates.


Vent: What is a Vent? A small hole or shallow channel in a mold that allows air or gas to exit as the molding material enters.

Vibration Resistance: What is Vibration Resistance? Vibration Resistance is the property of a material that indicates its ability to resist mechanical vibration without wearing away, setting or dusting.

Vinyl: What is Vinyl? The name of a class of resins or sheeting.

Viscosity: What is Viscosity? The tendency of a material to resist flow.

Void Content: What is Void Content? Volume percentage of voids, usually less than 1% in a properly cured composite. The experimental determination is indirect, meaning it is calculated from the measured density of a cured laminate and the "theoretical" density of the starting material.

Voids: What are Voids? Air or gas that has been trapped and cured into a laminate. Porosity is an aggregation of microvoids. Voids are essentially incapable of transmitting structural stresses or nonradiative energy fields.

Volatiles: What are Volatiles? Materials, such as water and alcohol, in a sizing or a resin formulation, that are capable of being driven off as a vapor at room temperature or at a slightly elevated temperature.

Volume Production: Do my composite Volumes have to be high (in the hundreds of thousands) to justify the investment in tooling?  Answer is “no”! Dyplast has already made the investment in tooling to accommodate the vast majority of composite shapes and applications; and Dyplast can fabricate sheets and shapes to close tolerances.


Warp: What is a Warp? A change in dimension of a cured laminate from its original molded shape.

Warpage: What is Warpage? The change in the flatness of a material caused by differences in the temperature and/or humidity applied to opposite surfaces of the material.

Water Absorption: What is Water Absorption? The increase in weight of a material expressed as a percentage of its dry weight or volume after: immersion in water for a specified time.

Water Resistant: What is Water Resistant? Capable of withstanding limited exposure to water.

Water Vapor Diffusion: What is Water Vapor Diffusion? The process by which water vapor spreads or moves through permeable materials caused by a: difference in water vapor pressure.

Water Vapor Permeability: What is Water Vapor Permeability? The time rate of water vapor transmission through unit area of flat material of unit thickness: induced by unit vapor pressure difference between two specific surfaces, under specified: temperature and humidity. Water vapor permeability is measured in perm inches.

Water Vapor Permeance: What is Water Vapor Permeance? The time rate of water vapor transmission through unit area of flat material or construction: induced by unit vapor pressure difference between two specific surfaces, under specified: temperature and humidity conditions. Water vapor permeance is measured in units: of perm.

Water Vapor Pressure: What is Water Vapor Pressure? The pressure of water vapor at a given temperature; also the component of atmospheric pressure contributed by the presence of water vapor.

Water Vapor Resistance: What is Water Vapor Resistance? The steady state vapor pressure difference that induces unit time rate of vapor flow through unit: area of a flat material (or construction that acts like a homogeneous body) for specific conditions: of temperature and relative humidity at each surface.

Water Vapor Retarder (Barrier): What is a Water Vapor Retarder (Barrier)? A material or system that significantly impedes the transmission of water vapor under specified: conditions.

Water Vapor Transmission Rate (WVTR): What is the Water Vapor Transmission Rate? The steady state water vapor flow in unit time through unit area of a body, normal to specific: parallel surfaces, under specific conditions of temperature and humidity at each surface. The I-P: units are lbs / hr – ft2; the SI units are grams / hr – m2.

Water Vapor: What is Water Vapor? Water Vapor is the gaseous state of liquid water. This gas phase of water and is colorless, odorless, and tasteless.

Waterproof: What is Waterproof? Impervious to prolonged exposure to water or water entry.

Weather Barrier: What is a Weather Barrier? A breather jacket or coating which allows passage of water vapor yet protects from atmospheric conditions.

Weave: What is Weave? The particular manner in which a fabric is formed by interlacing yarns. Usually assigned a style number.

Wetting and Adhesion, Surface: What is Surface Wetting and Adhesion? The mutual affinity of and bonding between finish and the surface to which it is applied.

Wicking: What is Wicking? A wicking material transports condensed water to the outside of the system for evaporation to the atmosphere. Wicking is the action of capillary action.

Wrinkle: What is a Wrinkle? A surface imperfection in laminated plastics that has the appearance of a crease or fold in one or more outer sheets of the paper, fabric, or other base, which has been pressed in. Also occurs in vacuum bag molding when the bag is improperly placed, causing a crease.


XPS vs. EPS: Why XPS vs. EPS? Both EPS and XPS are white, rigid, thermoplastic foams, typically manufactured in densities ranging from 0.8 to 2 pcf. As the name indicates, EPS is expanded into very large blocks. XPS is extruded, thus the billets are much smaller. XPS is considerably more expensive than EPS, yet the physical properties of each (at comparable densities) are actually quite similar, yet often advertised as quite different. Often the differences are due to the ASTM testing protocols and the fact that XPS may have “skins” on the surface prior to fabrication that affect, for example, water absorption. Also, whereas EPS is often advertised as wicking away any absorbed moisture, XPS does not.