Rubber Dictionary
ABRASION RESISTANCE
This property may be defined as the resistance of a specimen to abrasive wear. It is very important in tire treads, soles on heels, hose, rubber rollers and the covers of conveyor belts and cables.
ACID RESISTANCE
The resistance of the action of various acids either concentrated or diluted.
AGING
Accelerated aging tests are run on various rubber specimens to find out in a short period of time the destructive influence of light, oxygen, heat, cold and ozone. Natural or shelf aging requires many years for proper evaluation. Accelerated aging tests will give comparative values but not an absolute correlation to natural aging.
COMPRESSION SET
Is a permanent deformation to a specimen resulting from compressive stress. It is measured (1) as the amount by which a standard test piece fails to return to its original thickness after being subjected to a standard compressive load or deflection for a fixed period of time: or (2) as the distance returned relative to the amount deflected.
DIELECTRIC PROPERTIES
This is the ability of a material to resist a puncture due to electrical stress.
DUROMETER HARDNESS
Is the measurement most generally used for stating the hardness of elastic materials. For example, a rubber band is approximately 30 shore "A" hardness, tire tread stock is approximately 60 shore "A" hardness and a typical hard rubber shoe heel is about 80 shore "A" hardness.
ELASTOMER
A term used to describe elastic polymers with rubber-like behavior.
ELONGATION
Percent elongation or strain is the extension between 1" apart bench marks produced by a tensile force applied to a specimen. It is expressed as a percentage of the original distance between the marks. Ultimate elongation is the elongation at the moment of rupture.
FLAME RESISTANCE
This is the resistance of a specimen to burning, or material that will not support combustion under ordinary conditions.
FLEX CRACKING
Rubber specimens subjected to repeated flexing have been found to develop small cracks on the surface of the specimen.
HEAT RESISTANCE
This is the ability of rubber to retain its useful properties under the destructive influence of heat.
HYDROCARBON SOLVENTS (AROMATIC)
These solvents have basic benzene structure, usually coal tar types such as benzene, toluene and xylene.
LOW TEMPERATURE FLEXIBILITY
This is the temperature at which the rubber becomes too stiff to function in its intended manner.
MODULUS
The term modulus is used to express the amount of stress in pounds per square inch or psi required to stretch the test specimen to a given elongation. It expresses the resistance to extension or stiffness. A higher modulus means a stiffer material.
OXIDATION RESISTANCE
This is the ability of rubber to resist the reaction of atmospheric oxygen.
OXYGENATED SOLVENTS (ALIPHATIC)
Straight chain organic carbon structures such as petroleum type solvents.
PERMANENT SET
When a piece of rubber is stretched and released it does not return to its exact original length but comes to rest somewhat longer than it was before stretching. This increase in the length of the rubber, expressed as percent of original length, is termed "permanent set". Some people call this "memory".
PERMEABILITY
The ability or ease in which a liquid or gas can pass through a film of rubber.
RESILIENCE
Resilience is the ratio of return to impressed energy. It is usually expressed as a percent.
SPECIFIC GRAVITY
This is the ratio between the weight of unit volume of a specimen and the weight of the same volume in water at room temperature. This value is extremely helpful in identifying unmarked, black, rubber specimens. For example, Viton has a gravity of 1.83, Neoprene is 1.40, Nitrile is 1.24 and Natural is 1.10 (approximate values).
TENSILE STRENGTH
Tensile strength or stress is the force per cross-sectional area which is applied at the time of rupture of a specimen. It is usually expressed as pounds per square inch or psi.
