ASTM G114-21 PDF

SIGNIFICANCE AND USE 5.1 This practice allows the user to evaluate the effect of service or accelerating aging on the oxygen resistance of polymeric materials used in oxygen service. 5.2 The use of this practice presupposes that the properties used to evaluate the effect of aging can be shown to relate to the intended use of the material, and are also sensitive to the effect of aging. 5.3 Polymeric materials will, in general, be more susceptible than metals to aging effects as evidenced by irreversible property loss. Such property loss may lead to catastrophic component failure, including a secondary fire, before primary ignition or combustion of the polymeric material occurs. 5.4 Polymers aged in the presence of oxygen-containing media may undergo many types of reversible and irreversible physical and chemical property change. The severity of the aging conditions determines the extent and type of changes that take place. Polymers are not necessarily degraded by aging, but may be unchanged or improved. For example, aging may drive off volatile materials, thus raising the ignition temperature without compromising mechanical properties. However, aging under prolonged or severe conditions (for example, elevated oxygen concentration) will usually cause a decrease in mechanical performance, while improving resistance to ignition and combustion. 5.5 Aging may result in reversible mass increase (physisorption), irreversible mass increase (chemisorption), plasticization, discoloration, loss of volatiles, embrittlement, softening due to sorption of volatiles, cracking, relief of molding stresses, increased crystallinity, dimensional change, advance of cure in thermosets and elastomers, chain scissioning, and crosslinking. 5.6 After a period of service, a material’s properties may be significantly different from those when new. All materials rated for oxygen service should remain resistant to ignition and combustion (primary fire risk). Furthermore, all materials rated for oxygen s... SCOPE 1.1 These practices describe procedures that are used to determine the age resistance of plastic, thermosetting, elastomeric, and polymer matrix composite materials exposed to oxygen-containing media. 1.2 While these practices focus on evaluating the age resistance of polymeric materials in oxygen-containing media prior to ignition and combustion testing, they also have relevance for evaluating the age resistance of metals, and nonmetallic oils and greases. 1.3 These practices address both established procedures that have a foundation of experience and new procedures that have yet to be validated. The latter are included to promote research and later elaboration in this practice as methods of the former type. 1.4 The results of these practices may not give exact correlation with service performance since service conditions vary widely and may involve multiple factors such as those listed in 5.8. 1.5 Three procedures are described for evaluating the age resistance of polymeric materials depending on application and information sought. 1.5.1 Procedure A: Natural Aging—This procedure is used to simulate the effect(s) of one or more service stressors on a material’s oxygen resistance, and is suitable for evaluating materials that experience continuous or intermittent exposure to elevated temperature during service. 1.5.2 Procedure B: Accelerated Aging Comparative Oxygen Resistance—This procedure is suitable for evaluating materials that are used in ambient temperature service, or at a temperature that is otherwise lower than the aging temperature, and is useful for developing oxygen compatibility rankings on a laboratory comparison basis. 1.5.3 Procedure C: Accelerated Aging Lifetime Prediction—This procedure is used to determine the relationship between aging temperature and a fixed level of property change, thereby allowing predictions to be made about the effect of prolonged service on oxidative degra...