1.1本规程涵盖了热老化、自然或人工加速风化或化学暴露后热塑性塑料和热固性塑料性能保持指数（PRI）的计算程序。 1.2本规程的目的不是建立进行暴露试验的固定程序，而是提供一组特定程序，用于计算暴露后材料特性的保留指数。具体暴露试验条件的选择取决于被测材料和被测性能。由用户确定哪些暴露试验条件与所使用的特定材料和使用条件最相关。 使用的暴露试验必须根据特定暴露标准中描述的条件进行。 1.3本规程未描述待测试材料的取样程序。适用于被评估材料的标准和规范中描述了这些程序。 1.4用于计算PRI的程序取决于用于表征暴露材料的试验是破坏性的还是非破坏性的。PRI可用于描述材料经过暴露试验后，在指定温度下塑料的短期机械、电气和其他性能。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 注1-没有类似或等效的ISO标准。ISO DIS 11248有很大不同，因为它只适用于热固性树脂。

1.1 This practice covers procedures for the calculation of a property retention index (PRI) of thermoplastic and thermoset plastics after exposure to thermal aging, natural or artificial accelerated weathering, or chemical exposures. 1.2 This practice is not intended to establish a fixed procedure for conducting the exposure test, but it is intended to provide a set of specific procedures used to calculate the retention index of a characteristic property of the material after it has been exposed. Selection of the specific exposure test conditions depends on the material being tested and the property being measured. It is up to the user to determine which exposure test conditions are most relevant to the specific material and the service condition being used. The exposure test used must be conducted in accordance with conditions described in specific exposure standards. 1.3 This practice does not describe procedures for sampling the materials to be tested. These procedures are described in the standards and specifications applicable to the material being evaluated. 1.4 The procedure used to calculate the PRI depends on whether the test used to characterize the materials being exposed is destructive or nondestructive. The PRI can be useful in describing short-term mechanical, electrical, and other properties of plastics at specified temperatures after the materials have been subjected to an exposure test. 1.5 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. Note 1—There is no similar or equivalent ISO standard. ISO DIS 11248 is significantly different since it pertains only to thermosetting resins.