可熔融加工聚乙烯醇的非等温结晶分析

通过差示扫描量热法(DSC)测试了成核剂对可熔融加工改性聚乙烯醇(PVA)结晶行为的影响,并在DSC的基础上用Ozawa法、Jeziorny法以及莫志深方法分析了改性PVA以及改性PVA/成核剂两种材料的非等温结晶动力学。结果表明:结晶度、结晶峰温度、结晶半衰期、结晶速率对降温速率有很强的依赖性;随着降温速率的增加,结晶速率常数增大,结晶度提高;在相同的降温速率下,复合体系的结晶速率常数较大,即成核剂的加入使改性PVA的结晶速率增加,具有异相成核的作用;其中莫志深方法能够较好地解释改性PVA的非等温结晶过程。

Non-Isothermal Crystallization Behaviors of Melt Processable Polyvinyl Alcohol

The non-isothermal crystallization behaviors of melt processable modified polyvinyl alcohol(PVA)/nucleating agent composite were investigated by differential scanning calorimetry(DSC). The non-isother-mal crystallization kinetics of the two materials were analyzed by Ozawa,Jeziorny and Mo Zhishen methods.The results showed that crystallinity,crystallization peak temperature,t_(1/2),crystallization rate depended onthe cooling rate significantiy. With the increase of the cooling rate,the crystallization rate constant and thecrystallinity were increased. Moreover,at the same cooling rate,the crystallization rate of the PVA/nucleat-ing agent composite was larger than modified PVA. This indicated that the addition of nucleating agentcould increase the crystallization rate of the modified PVA and had the effect of heterogeneous nucleation.The Mo Zhishen method could better explain the non-isothermal crystallization process of modified PVA.