Preparation And Properties Test Of T-ZnOw/PS Composites

Tetrapod-shaped zinc oxide whisker (T-ZnOw) is inorganic crystal material with three-dimensional space structure. The angle between each random two needles is 109°. As a result of random orientation of T-ZnOw in the matrix, composites modified by T-ZnOw show the isotropic properties. T-ZnOw could simultaneously improve the tougthness and stiffness of composites due to structure characteristic of T-ZnOw. Tetra-needle-shaped structure of T-ZnOw is easily broken by the tensile stress and shear stress during the processing process, and in the condition T-ZnOw becomes the traditional one-dimensional whisker. Generally, the breaking of T-ZnOw happens from the growing point of T-ZnOw, which induces many needles or fragment of T-ZnOw. The existence of T-ZnOw fragment could induce the decrease of composites properties. It is very important to investigate an appropriate composites preparation method so as to keep the typical tetra-needle-shaped structure of T-ZnOw, and it is also very signification to research the strengthening and toughening of T-ZnOw on polymer composites.The fractal structure of tetra-needle-shaped zinc oxide whisker (T-ZnOw) was used to prepare T-ZnOw/Polystyrene (PS) composites via the combination of solution blending and injection moulding methods. The mechanical and thermal properties of the composites were measured in this work. The fracture mechanism of composites was analyzed in order to study the effect of T-ZnOw in the matrix. The results show that T-ZnOw could improve the impact strength and tensile modulus. Scanning Electron Microscope (SEM) results of tensile--fractured surface show that the pulling out of T-ZnOw and the breaking of T-ZnOw are the main fracture mechanisms of composites during the tensile processing. SEM results of impact--fractured surface show that the main reason for the increasing of toughness of composites is the formation of many crazes. Thesse are induced by T-ZnOw during the impact process. The result of thermal properties show that heat degradation temperature (Td) of the composites is greatly improved, however heat deflection temperature (TDT) and glass transition temperature (Tg) have no extinct change.In order to further research the effect of interfacial interaction between T-ZnOw and matrix, different coupling agents were used to surface modifify of T-ZnOw. Furthermore, different surface modification methods of T-ZnOw and different molding methods were investigated in this work to research the effect of processing conditions on the morphology and properties of T-ZnOw/PS composites. The mechanical properties and thermal properties of T-ZnOw/PS composite were studied. The results show that titanate coupling agent (NDZ-105) with the longer flexible chain is more effective in improving impact strength of composites, but silane coupling agent (KH-560) is more superior in improving stiffness of composites. However the influences of coupling agent types on thermal properties of composites are not obvious. The different surface modification methods of T-ZnOw (dry treatment method or web treatment method) have no effect on the mechanical properties and thermal properties. In improving mechanical properties and thermal deflection temperature of, the composites by compression molding are better than composites by injection molding. The results show that the structures of some tetra-needle-shaped whiskers are broken by shear stress in injection processing of composites although the breaking of whiskers are avoided in solution blending of composites, Thus the properties of composites by compression molding are better superior than composites by injection moulding. But the results are just opposite in improving Td of composites. Different processes molding methods have on effect on Tg of composites.