Rheological, mechanical and thermal properties of the PA/PVB blends and their nanocomposites: Structure-property relationships

Different PA/PVB blends and PA/PVB/nanoclay nanocomposites were prepared and their rheological, mechanical and thermal properties were studied and correlated with their phase morphology. According to the morphological observations, phase inversion occurred near 60 wt% PVB. Also, the TEM micrographs showed that nanoclay particles mostly localized in the interface of the PA and PVB phases. The rheological properties of the blends were considerably influenced by the morphological changes. In fact, increase in the PVB weight fraction and nanofiller content led to changes in flow behavior of the samples, especially near the phase inversion point. Good agreement between the experimental results and predictions of different models were seen for the tensile behavior of the blends. The blends containing 50-60 wt% PVB possessed promising impact strengths. Furthermore, localization of the Cloisite 30B at the interface helped to achieve extensive plastic deformation, and hence high toughness for the PA/PVB50 blend filled with 1 phr nanoclay. Investigation of Izod impact-fractured surfaces showed that cavitation and multiple crazing are the main toughening mechanisms in the blends. The TGA analysis suggested that the thermal degradation of the PVB is improved by blending with PA, while incorporation of nanoclay didn't have any significant effect on thermal stability of the blends.