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Abrasion
Wear due to friction.
Abrasion Test
Determination of the rate of wearing away by friction.
Additive
A material which does not affect the chemical reaction but is included to alter the final product, such as fillers, flame retardant, etc.
Adhesion
Basically, the adhering, clinging, bonding or sticking of two material surfaces to one another, such as polyurethane to polyurethane, polyurethane to metal, polyurethane to rubber, etc.
Aging
The undergo changes in physical properties with age or lapse of time.
Ambient Temperature
The environment temperature surrounding the object under consideration.
Anti-static
Capability to conduct static electricity.
ASME
American Society of Mechanical Engineers.
ASTM
American Society for Testing and Materials.
Average Modulus
The total change of stress divided by the total change of strain.
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Bench Test
A modified service test in which the service conditions are approximated in the laboratory.
Bending Force
The force required to bend a given cross-section under prescribed conditions.
Bending Modulus
The force required to induce bending around a specified radius and hence, a measure of stiffness.
Blemish
A mark, deformity, or injury, which impairs the appearance.
Bond
Basically, the adhering, clinging, bonding or sticking of two material surfaces to one another, such as polyurethane to polyurethane, polyurethane to metal, polyurethane to rubber, etc.
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Casting
The process of filling (pouring) open molds with liquid (uncured) polyurethane.
Catalyst
The ingredient in polyurethane which initiates a chemical reaction or increases the rate of chemical reaction.
Chain Reaction
Lengthening of the main chain (backbone) of polymer molecules by end-to-end attachment.
Chute Lining
Highly abrasion-resistant elastomeric (polyurethane) lining in a chute to protect the metal chute from abrasion wear.
Coefficient of Friction
The ratio of the force required to move an object across a surface to the weight of an object.
Conductivity
Quality of power of conducting or transmitting heat or electricity.
Cross Linking
The formation of chemical links between molecular chains.
Cure
The process which completes the chemical reaction. The term also refers to the state of completeness of the chemical reaction.
Cure Time
Time required, at a given temperature, to produce optimum
physical properties in an elastomer.
Curing Agent
An additive that increases chemical activity between the components, resulting in an increase or decrease in the rate of cure.
Curing Temperature
The temperature at which the elastomer product is cured.
Cut Resistance
The ability of polyurethane to withstand the cutting action of sharp objects.
Cycle Time
The amount of time required to complete a molding cycle, including mold preparation, insert loading (when applicable), release agent application (when required), mixing and dispensing of components, reaction (preliminary cure), and demolding.
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Degradation
A deleterious change in the chemical structure of a material.
Delamination
The separation of layers of material in a laminate.
Density
The ratio of the mass of a body to its volume or the mass per unit volume of the substance. For ordinary practical purposes, density and specific gravity may be regarded as equivalent.
Durometer
An instrument for measuring the hardness of polyurethane. Measures the resistance to the penetration of an indenter point into the surface of rubber.
Durometer Hardness
An arbitrary numerical value which measures the resistance to penetration of the indenter point of the durometer. Value may be taken immediately or after a very short specified time.
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Elasticity
The property of an article which tends to return it to its original shape after deformation.
Elastomer
An elastic, rubber-like substance, such as polyurethane or synthetic rubber.
Elastomeric Properties
The chemical and physical properties of an elastomer.
Elongation
Increase in length before rupture occurs, expressed numerically as a fraction or percentage of initial length.
Embossing
Operation of transferring a design to a polyurethane surface.
Exotherm
Heat generated by a chemical reaction.
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Fatigue
The weakening or deterioration of a material caused by a repetition of stress or strain.
Fire Resistance
Intensity of flame diminished by fire retardant ingredient(s) in the polymer compound.
Fire Resistant
Retards the burning action of fire or flame.
Flame Retardance
Intensity of flame diminished by fire retardant ingredient(s) in the polymer compound.
Flame Retardant
A substance (additive) which is added to a polymer formulation to reduce or retard its tendency to burn.
Flame Test
A means, under specific condition, for establishing the flame performance of a polyurethane product. This will not indicate the performance of the product in any fire in which the product may be involved.
Flange
A raised edge on a polyurethane article.
Flash
Material protruding from the surface of a molded part, appearing at the mold parting line or mold vent points.
Flexibility
The ability to be bent repeatedly without cracking.
Friction
(1) The resistance to motion of any object, due to the contact between two surfaces. (2) Improperly used to indicate the bond between two surfaces.
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Gel
The initial semi-solid stage that develops during the solvation of a resin by a plasticizer.
Gel Point
The stage at which liquid begins to exhibit pseudo-elastic properties.
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Hardening
An increase in resistance to indentation.
Hardness
Property or extent of being hard. Measured by extent of failure of the indenter point of any one of a number of standard hardness testing instruments to penetrate the product.
Heat Degradation
Change in chemical and/or physical properties due to excessive exposure to heat.
Homogenous
Of uniform composition throughout.
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Impact
The single instantaneous stroke or contact of a moving body with another either moving or at rest, such as a large mass of heavy material dropping on polyurethane product.
Impact Energy
The effective combination of force (weight of the body and height) when one body falls on another.
Impact Force
The energy power of impact.
Impact Resistance
The relative ability to withstand mechanical or physical blows without the loss of protective properties.
Injection Molding
A method frequently utilized in the manufacture of polyurethane products. While this method is extremely cost-effective when producing huge quantities, the properties of the injection-molded polymers (thermoplastics) do not offer the superior characteristics of "open cast" (thermoset) polyurethane.
ISO
The abbreviation for the International Organization for Standardization.
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Joint
The area where two ends of a component are fastened together, either by chemical or mechanical means.
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Laminate
A product made by bonding together two or more layers of material.
Lap
A part that extends over itself or a like part.
Lap Seam
A seam made by placing the edge of one piece of material extending flat over the edge of the second piece of material.
Lateral
Coming from the side.
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MDI
The abbreviated term for diphenylmethane diisocyanate.
Modulus
(1) A coefficient or numerical measure of some property.
(2) In polymers, modulus usually refers to one of several measurements of stiffness
or resistance to deformation. The use of the word without modifying terms may
be confusing and such use should not be encouraged. Modulus in polyurethane
may be either static or dynamic; static moduli are subdivided into tangent,
chord and compounders. Compounders modulus is always in tension, but the others
may be in shear, compression or tension. Other terms used in connection with "modulus" are
elasticity, rigidity, Young's tangent and elongation. (3) All elastic moduli
in rubber (except compounder's) are ratios of stress to the strain produced
by that stress, the stress, usually PSI.
Modulus of Elasticity
The force divided by the percent elongation (divided by 100) to cause the elongation.
Mold Lubricant
The material used to coat the surfaces of a mold to prevent the polyurethane adhering to the metal during the initial chemical reaction (cure).
Mold Release
The material used to coat the surfaces of a mold to prevent the polyurethane adhering to the metal during the initial chemical reaction (cure).
MSHA
Abbreviation for Mine Safety and Health Administration.
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NCO
Abbreviation for nitrogen, carbon, oxygen.
NDI
Abbreviation for naphthalene diisocyanate.
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Oil Proof
Not adversely affected by exposure to oil.
Oil Resistant
Withstands the deterioration effect of oil (generally refers to petroleum) on the physical properties.
Open Cast
The method of manufacture utilized to obtain maximum wear characteristics in polyurethane modules.
Optimum Cure
The time and temperature of fusion at which a desired combination of properties is attained in an elastomer.
Oven
A low pressure hot air chamber equipped with precise temperature controls, used for the purpose of post curing open cast polyurethane products.
Ozone Resistant
Withstands the deteriorating effects of ozone (generally cracking).
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Permanent Set
The amount by which an elastic material fails to return to its original form after deformation.
Permeability
The quality or condition of allowing passage of liquids or gases through a material layer.
Physical Properties
A measure of mechanical characteristics of a material.
Polyester
A polymeric compound, with the reactive hydroxyl groups containing ester linkages.
Polyether
A polymeric compound, with the reactive hydroxyl groups containing ether linkages.
Polymer
A macromolecular material formed by the chemical combination of monomers having either the same or different chemical composition.
Polyol
A chemical compound with more than one reactive hydroxyl group attached to the molecule.
Post Cure
The period of cure after the product has been removed from the mold. In many cases, accelerated curing at elevated temperatures is utilized.
Pot Life
The period of time during which a reacting polymeric compound remains suitable for its intended use after having been mixed with a reaction-initiating agent.
Prepolymer
A chemical intermediate, manufactured by reacting all the isocyanate with a portion (or all) of the polyol.
PTMEG
Polytetramethylene Glycol
PU
The abbreviation of polyurethane.
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Resistance
The property or ability of matter to withstand the effects of force, pressure, heat or chemical action.
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Sample
A piece of material removed for evaluation.
Scraper
An open cast polyurethane device for cleaning the surface of conveyor belting.
Seam
The place where two edges of fabric or elastomer are adjacent to each other to form a single ply or layer.
Semi-cure
A partial or incomplete cure.
Set
The amount of deformation remaining after complete release of the load, producing the deformation.
Sheeting
A form of plastic in which the thickness is very small in proportion to length and width and in which the plastic is present as a continuous phase throughout.
Shelf Storage Life
The period of time prior to use during which a product retains its intended performance capability.
Shore Hardness
The scale by which a polyurethane screen module or component is measured for hardness, typically expressed as "shore A." As the hardness is increased, abrasion resistance tends to increase, which impact resistance decreases proportionately. As the hardness is decreased, abrasion resistance tends to decrease which impact resistance increases proportionately.
Shrinkage
The difference found on a molded part as compared to the actual mold cavity dimension. The typical shrinkage for thermoset polyurethane is about 2%.
Sink
A collapsed blister or bubble, leaving a depression in a product.
Skive
A cut made on an angle to the surface to produce a tapered or feathered cut.
Specification
Detailed description of specific requirements.
Static Conductive
Capability to conduct static electricity.
Static Electricity
Electrical potential resulting from two surfaces rubbing together or parting one from the other.
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Tear Propagation
Continuation of tear.
Tensile Strength
The maximum of force, stress, applied to a specimen at rupture.
Tensile Stress
The force applied to stretch a test piece (specimen).
Tension
Stress on a material, tending to cause extension of the material.
TDI
Abbreviation for toluene diisocyanate.
Tolerance
The limiting values for a dimension.
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Ultimate Elongation
Elongation at rupture.
Ultimate Strength
The force required to rupture a specimen.
Ultimate Tensile
Tensile stress at rupture.
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Viscosity
The flow property of material. The lower the number, the thinner the liquid.
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Yield Strength
The stress at which a material exhibits a specified limiting permanent set. Determined by a measurable value of plastic yielding of the material, above which the material is considered to be damaged and below which the damaging effects are considered to be negligible.
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