热塑性聚氨酯及其复合材料的界面形态与流变特性

以聚酯型热塑性聚氨酯(thermoplastic polyurethane,TPU)、玻璃纤维(glass fiber,GF)和玻璃微珠(glass bead,GB)为主要原料制备了TPU/GF、TPU/GB共混物,考察了复合体系的热性能、微观结构、动态流变特性.研究发现,TPU是温敏型聚合物,其温敏性与材料的硬段含量有关,在加工过程中,除考虑剪切速率的影响外,需重点考虑温度对其加工性能的影响;GF,GB填充TPU体系具有良好的分散形态和界面结合牢度,GF和GB的加入能够增加体系的黏度,降低TPU的温敏性,加宽TPU的加工温度窗口,从而改善其成型加工性,并能一定程度地提高其耐热性.研究还发现,复合体系黏度的增加程度不仅和填料的含量有关,而且与填料的形状有关,可用等效直径表征.另外,从比表面积的角度比较了玻璃纤维和玻璃微珠对体系热稳定性的影响.

MICROSTRUCTURE AND RHEOLOGICAL PROPERTIES OF THERMOPLASTIC POLYURETHANE AND ITS COMPOSITES

Thermoplastic polyurethane(TPU) and its composites filled with glass fiber(GF) or glass beads(GB) were studied,which were prepared by incorporation of antioxidant,dispersant and release agent via melt blending.The effects of fillers on the thermal properties,microstructure and rheological behavior of TPU were investigated by TGA,SEM and dynamic rheological test.Dynamic rheological studies showed that TPU was of thermal-sensitivity,determined by the hard segment content of the molecular chains.Hence,in addition to shear effect,the effect of temperature was needed to be especially considered during processing.By means of small amplitude oscillatory shear method,the effects of the fillers on the rheological properties of TPU matrix were obtained,and the results indicated that the fillers endowed the composites with higher complex viscosity,lower thermal-sensitivity,broader scale of processing temperature and better processing ability.The filler shapes as well as filler content showed big effects on the increasing of complex viscosity,which could be analyzed by equivalent diameter.The SEM studies indicated that the GF or GB dispersed well and had good interfacial interactions with the TPU matrix,thus resulting in better heat resistance of the composites compared with pure TPU,which was reflected in thermal gravimetric curves.What's more,the effects of GF and GB on thermal properties of TPU were analyzed from the point of view of specific surface area.