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.