氮气保护在PP熔体流动速率测试中的作用

Function of N_2 atmosphere in test of melt flow rate of PP

通过比较在有、无氮气保护的情况下聚丙烯(PP)熔体质量流动速率和熔体体积流动速率测试值的不同,探讨了PP熔体流动速率测试过程中氮气保护的作用。无氮气情况下PP在高温发生热氧化降解,分子链断裂,熔体变稀,致使测得的熔体流动速率值偏大;使用氮气吹扫可有效保护试样,更准确地测定熔体流动速率。

This paper probed into the function of N2 atmosphere in the process of measuring melt flow rate of polypropylene （PP） via comparison of the melt mass-flow rate and the melt volume-flow rate of PP tested with and without N2 protection. In the absence of N2 gas, PP tended to be subject to thermooxidative degradation, molecular chain cleavage and thinning down of the melt, resulted in an exorbitant somewhat melt flow rate. Purging with nitrogen could effectively protect the specimen from degradation and help to determine melt flow rate of PP more precisely