本文件规定了两种测定氯乙烯均聚物和共聚物（下文中简称PVC）产品和化合物热稳定性的方法，即当其以片材形式暴露于高温下时发生变色的程度。这两种方法是:-方法A:油浴法；-方法B:烘箱法。这些方法特别适用于测定聚氯乙烯的耐热性，通过在标准条件下加热不同时间后颜色的变化来评估。结果仅是比较性的，当对有色PVC材料进行测试时，结果可能不令人满意。两种方法给出的稳定时间可能不相似，不能用于直接比较。

This document specifies two methods for the determination of the thermal stability of products and compounds based on vinyl chloride homopolymers and copolymers (referred to simply as PVC in the following text) by the extent of the discoloration that occurs when they are exposed, in the form of sheet, to elevated temperatures. The two methods are: — Method A: Oil-bath method; — Method B: Oven method. These methods are particularly applicable to the determination of the resistance of PVC to degradation by heat, as assessed by the change in colour after different times of heating under standardized conditions. The results are comparative only, and can be unsatisfactory when coloured PVC materials are tested. The stability times given by the two methods might not be similar and cannot be used for direct-comparison purposes.