PTFE/PA6和PTFE/PA66共混物的吸水性及流变行为

通过浸水实验、缺口冲击断裂实验和动态流变测试,考察了PTFE含量对PTFE/PA6和PTFE/PA66共混物的吸水率、冲击断裂强度及熔体黏度的影响以及熔体黏度随温度和频率的变化规律。结果表明,PTFE/PA6和PTFE/PA66共混物的吸水率均随着PTFE含量的增加而减小,即PTFE的加入抑制了共混物的吸水性。两种共混物的冲击强度比纯PA明显降低,但是吸收水对两种共混物冲击强度的影响不显著。随着PTFE含量的增加,共混物熔体的黏度先减小后增加,说明适量的PTFE可以改善共混物的成型加工特性。共混物熔体的黏度随加载频率的增大而降低,符合假塑性流体流动规律。有趣的是,对于PTFE/PA6共混物的黏度随着温度的升高而减小,而PTFE/PA66共混物黏度随着温度升高近似成指数规律增大。

Experimental Studies on Water-Absorptivity and Rheological Behavior of PTFE/PA6 and PTFE/PA66 Blends

The effects of PTFE content on water-absorptivity,notched impact strength and complex viscosity of PTFE/PA6 and PTFE/PA66 blends were investigated by water immersion test,Charpy impact fracture test and dynamic rheology measurement in this paper.It is shown that the amount of absorbed water in the blends decreases with increasing PTFE content,indicating that the PTFE phase restrains the PA phase from water absorption.Although the addition of PTFE causes a decrease in notched impact strength of the blends,as compared to pure PA,the absorbed water has little effects on the notched impact strength of the blends.It is also shown that the complex viscosity of the blends varies with the PTFE content;an appropriate content of PTFE can improve the processability of the blends.Moreover the complex viscosity of the blend melts decreases with increasing frequency at given temperatures,which exhibits pseudoplastic behavior.As to the temperature dependence of complex viscosity of the blend melts,an interesting phenomenon was observed.The complex viscosity decreases with increasing temperature for PTFE/PA6 melts,while it increases with temperature in a manner of power law for PTFE/PA66 melts.