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Standard Practice for Rubber Conditioning For Low Temperature Testing
Automaticky přeložený název:
Standardní praxe na pryž úprava za nízké testování teploty
NORMA vydána dne 1.12.2012
Označení normy: ASTM D832-07(2012)
Poznámka: NEPLATNÁ
Datum vydání normy: 1.12.2012
Kód zboží: NS-39416
Počet stran: 4
Přibližná hmotnost: 12 g (0.03 liber)
Země: Americká technická norma
Kategorie: Technické normy ASTM
Keywords:
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)
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. |
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1. Scope | ||
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: Property |
Crystallization |
Glass Transition |
Physical effects Becomes stiff (hard) but not necessarily brittle |
Becomes stiff and brittle |
|
Temperature-volume relation 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 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 Optimum temperature is specific to the polymer involved. |
Very wide limits, depending on composition |
|
Effect on molecular structure Orientation of molecular segments; random if unstrained, approaching parrallelism under strain |
Change in type of motion of segments of molecule |
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Materials exhibiting 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. |
All |
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.
Standard Terminology Relating to Rubber (Includes all amendments and changes 11/10/2021). |
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Standard Test Method for Coated Fabrics—Low-Temperature Bend Test (Includes all amendments and changes 3/19/2021). |
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Standard Test Method for Rubber Property—Effect of Liquids (Includes all amendments and changes 6/25/2021). |
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Standard Practice for Rubber IRM 901, IRM 902, and IRM 903 Replacement Oils for ASTM No. 1, ASTM No. 2, ASTM No. 3 Oils, and IRM 905 formerly ASTM No. 5 Oil |
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Standard Test Methods for Rubber Property´Stiffening at Low Temperatures: Flexible Polymers and Coated Fabrics (Includes all amendments and changes 9/19/2018). |
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Standard Test Method for Evaluating Rubber Property—Retraction at Lower Temperatures (TR Test) |
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