Significance and Use
3.1 Low temperature testing of rubber can yield repeatable results only if the preconditioning of the samples is consistent. Properties such as brittleness and modulus are greatly affected by variations in time/temperature exposures. This practice is intended to provide uniform conditioning for the various low temperature tests conducted on rubbers.
1.1 This practice covers the characteristic mechanical behavior of rubbers at low temperatures, and outlines the conditioning procedure necessary for testing at these temperatures.
1.2 One of the first stages in establishing a satisfactory technique for low temperature testing is the specification of the time and temperature of exposure of the test specimen. It has been demonstrated that any one or more of the following distinct changes, which are detailed in Table 1, may take place on lowering the test temperature:
TABLE 1 Differentiation Between Crystallization and Glass Transition
(1, 2, 4, 6, 7)A
Becomes stiff (hard) but not necessarily brittle
Becomes stiff and brittle
(1, 2, 3, 4, 5, 8)
Significant decrease in volume
No change in volume, but definite change in coefficient of thermal expansion
Latent heat effect (4, 5, 8)
Heat evolved on crystallization
Usually no heat effect, but definite change in specific heat
Rate (2, 4, 6, 7, 8)
Minutes, hours, days, or even months may be required. In general, as temperature is lowered, rate increases to a maximum and then decreases with increase in deformation. Rate also varies with composition, state of cure, and nuclei remaining from previous crystallizations, or from compounding materials such as carbon black.
Usually rapid; takes place within a definite narrow temperature range regardless of thermal history of specimen. May be limited rate effect (2)
Temperature of occurrence
(4, 5, 7, 8
Optimum temperature is specific to the polymer involved.
Very wide limits, depending on composition
Effect on molecular structure
(1, 2, 5, 6, 8)
Orientation of molecular segments; random if unstrained, approaching parrallelism under strain
Change in type of motion of segments of molecule
properties (5, 7, 8)
Unstretched polymers including natural rubber (low sulfur vulcanizates), chloroprene, Thiokol A polysulfide rubber, butadiene copolymers with high butadiene content, most silicones, some polyurethanes. Butyl rubbers crystallize when strained. Straining increases rate of crystallization of all of the above materials.
1.2.1 Simple temperature effects,
1.2.2 Glass transitions, and
1.2.3 First order transitions (crystallization), and solubility and other effects associated with plasticizers.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D471 Test Method for Rubber Property--Effect of Liquids
D1053 Test Methods for Rubber Property--Stiffening at Low Temperatures: Flexible Polymers and Coated Fabrics
D1329 Test Method for Evaluating Rubber Property--Retraction at Lower Temperatures (TR Test)
D1566 Terminology Relating to Rubber
D2136 Test Method for Coated Fabrics--Low-Temperature Bend Test
D5964 Practice for Rubber IRM 901, IRM 902, and IRM 903 Replacement Oils forASTM No. 1, ASTM No. 2, and ASTM No. 3 Oils
brittleness; brittle point; crystallization; enthalpy; first order transition; glass transition; low temperature test; modulus; plasticizer effects; resilience; second order transition; simple temperature effects; solubility; stiffening; subnormal temperature; thermodynamic change; viscoelasticity;
ICS Number Code 83.040.10 (Latex and raw rubber)
ASTM International is a member of CrossRef.
Citing ASTM Standards
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