Essential Material Properties Glossary for Plastics

Arc Resistance

Definition: The time a material resists forming a surface-conducting path when subjected to an arc of high voltage and low current.

Tests: ASTM D495

Coefficient of Thermal Expansion

Definition: The tendency of a material to expand when heated, quantified as the fractional change in size per degree of temperature change.

Tests: ASTM E831 (TMA), ASTM D696, ISO 11359

Deflection Temperature

Definition: The temperature at which a polymer or plastic sample deforms under a specified load in a three-point configuration.

Tests: ASTM D648, ISO 75

Dielectric Constant

Definition: A measure of a material's ability to resist the formation of an electric field. High values indicate the ability to hold large charges.

Tests: IEC 250, ASTM D150

Dielectric Strength

Definition: The maximum voltage per unit thickness a material can handle before electrical breakdown occurs.

Tests: IEC 243, ASTM D149

Dissipation Factor

Definition: The percentage of electrical energy lost when electrical current is applied to an insulating material.

Tests: IEC 250, ASTM D150

Elongation

Definition: The percentage increase in length of a material when placed under tension.

Tests: ASTM D638, ISO 527

Flame Spread

Definition: A measure of a material's tendency to transmit fire to other materials, quantified by factors like flame height and burning rate.

Tests: ASTM E84

Flammability Rating

Definition: A classification of how easily a material catches fire, with ratings such as 94HB, 94V-2, 94V-0, and 94-5VB.

Tests: UL 94

Flexural Modulus

Definition: The ratio of stress to strain in a material under flexural deformation, indicative of how much the material bends.

Tests: ISO 178, ASTM D790

Flexural Strength

Definition: The measure of a material's ability to resist deformation when under load.

Tests: ISO 178, ASTM D790

Hardness

Definition: A measure of how resistant a material is to various kinds of permanent shape change when a force is applied.

Tests: Rockwell E, Rockwell M, Rockwell R, Rockwell L, Shore A, Shore D

Impact Strength

Definition: The toughness of a material, measured by its ability to absorb energy during deformation.

Tests: ASTM D256, ISO 180

Specific Gravity

Definition: The ratio of the density of a material to the density of water at the same temperature.

Tests: ASTM D792, ISO 1183

Specific Volume

Definition: The ratio of a substance’s volume to its mass; it is inversely proportional to density.

Tests: ASTM D792, ISO 1183

Thermal Conductivity

Definition: The rate of heat flow through a material per unit thickness per degree of temperature difference across the thickness.

Tests: ASTM C177, ISO 8302

Tensile Modulus

Definition: The ratio of stress to elastic strain in a material in tension; lower values indicate a material stretches more.

Tests: ASTM D638, ISO 527

Tensile Strength

Definition: The force per unit area required to break a material by stretching.

Tests: ASTM D638, ISO 527

Volume Resistivity

Definition: The insulating material's ability to resist leakage current.

Tests: ASTM D257, IEC 93

Water Absorption

Definition: The percentage increase in weight of a material after exposure to water under specified conditions.

Tests: ASTM D570, ISO 62

Yield Strength

Definition: The stress at which a material begins to deform plastically.

Tests: ASTM E8

Creep Resistance

Definition: The ability of a material to resist long-term deformation under sustained load.

Tests: ASTM E139

Poisson's Ratio

Definition: The ratio of transverse strain to axial strain in a material under tension.

Tests: ASTM E132

Thermal Shock Resistance

Definition: The ability of a material to withstand rapid temperature changes without damage.

Tests: ASTM C1525

Wear Resistance

Definition: The ability of a material to resist wear and tear during surface contact with other materials.

Tests: ASTM G65