The Preparation And Properties Of The ASA/PVC Alloys And Its Composites

ASA was widely used in color co-extrusion profiles of PVC. In the practical application, scraping on surface and cracking defects between the co-extrusion layers were discovered frequently. Withal, PVC owned the outstanding characteristics of wear resistance, stiffness, flame retardant and inexpensive price. Therefore, it has a very important practical significance by blending the ASA with PVC in order to achieve superior performance. But the insufficient of performance can been detected in the ASA/PVC alloys still, so the further modification of alloys is necessary.The main contents and results of this study are introduced as follows:（1） The effects of different rubber content of ASA and different molecular weight of PVC on the macro-performance, compatibility, and wear resistance were researched in ASA/PVC alloys. The results showed that ASA owning higher rubber content and PVC possessing higher molecular weight resulted in better comprehensive mechanics performance of ASA/PVC alloys. With increasing the content of PVC, the tensile strength, flexural strength and wear resistance were improved obviously, and the hardness of ASA/PVC alloys changed slightly. The optimal comprehensive properties of ASA/PVC alloys were achieved at the mass ratio of 60/40, meanwhile, the alloys owned the superior impact strength with 8.5 kJ/m2. In addition, the characterization of SEM and DMA indicated that there was a certain compatibility between ASA and PVC, and the compatible system is incomplete.（2） The CPE was used to modify ASA/PVC（60/40） alloy. The dependence of impact properties and deformation mechanism on the entanglement density of CPE-modified ASA/PVC blends was investigated. The relationship among property, phase morphology and entanglement density of chain was built. It was found that the entanglement density and impact strength of ASA/PVC/CPE blends increased and the wear resistance improved with increasing of CPE content. The entanglement density and impact strength of alloys reached maximum when 15 wt% CPE was added. The micro-morphology was observed by SEM to elucidate the deformation mechanisms. Cavitation was the main deformation mechanism when the entanglement density of the matrix was low, while for the matrix with high entanglement density, shear yielding was the main deformation mechanism. In addition, with the increase of CPE, the tensile strength and flexural strength decreased gradually, and the thermal properties of alloys changed slightly.（3） The nano-CaCO₃ was used to modify ASA/PVC/CPE（60/40/15） alloy. The mechanical properties and morphology of ASA/PVC/CPE/nano-CaCO₃ composites were characterized by pendulum impact tester and SEM. Contact angle tester and rotational rheometer were used to illuminate the selective distribution of nano-CaCO₃ and the establishment of the CPE network structure. The results showed that, the tensile strength, flexural strength and thermal properties of the composites changed slightly with the increase of nano-CaCO₃. In addition, the wear resistance further enhanced, and the impact strength reached maximum when 4 wt% nano-CaCO₃ was added. Nano-CaCO₃ was selectively distributed within ASA/PVC and gathered at the inwall of CPE. Nano-CaCO₃ tended to promote the continuity of CPE, hence the stress around CPE phase could be connected with each other, and the impact energy could be availably dissipated. It concluded that the shear yielding in the crack propagation zone was the main deformation mechanism.