ASTM D6437-22 聚氨酯原材料的标准试验方法:低碱度多元醇中的碱度(多元醇CPR值的测定) Standard Test Method for Polyurethane Raw Materials: Alkalinity in Low-Alkalinity Polyols (Determination of CPR Values of Polyols) 预览ASTM D6437-22前三页