Studies On Synthesis And Mechanical Properties Of ASA Resins

ASA(Acrylate-Styrene-Acrylonitrile)resin was prepared by melt blending of acrylonitrile-styrene-acrylic graft copolymer with styrene-acrylonitrile (SAN) resin. The acrylonitrile-styrene-acrylic graft copolymer was synthesized by seeded emulsion polymerization, which has a typical core-shell structure modifier with a cross-linking polyacrylic core and a grafted styrene-acrylonitrile shell. And the grafted SAN chains acted as compatilizer with PSAN matrix in the ASA resin. Since the core of the graft copolymer is polyacrylate rubber with saturated structure, the chain is stable and can not be decomposed by light. ASA resin has the comparable mechanical properties with ABS resin and excellent weatherability, chemical resistance and colorability compared with ABS resin. Nowadays ASA resin has become the substitute product of ABS resin used in outdoor. ASA resin was first realized industrialization by German BASF of in 1968. And UMGABS Kabushiki Kaisha of Japan and America General Electric Company realized the industrialization in 1980 and 1984, respectively. Commercial alloy based ASA resin, such as PC/ASA alloy, PVC/ASA alloy; PBT/ASA resin and PMMA/ASA resin have been used widely. Since the main production technology of ASA resin and ASA alloy were mastered by foreign large enterprise, the research work is desiderate to development in our country.In this paper, the work was focused on the preparation technology of ASA resin, PC/ASA alloy and PVC/ASA alloy. The main research works and conclusions are as follows:1. The research on mechanism of CHP/FES/EDTA/SFS interfacial redox initiator system in seeded emulsion polymerization of butyl acrylate was carried. By the seeded emulsion polymerization it can realize the effective controlling of the particle size and a higher monomer conversion up to 99%. It was found that in the reaction the initial polymerization rate was slow, and with the prolongation of reaction time auto-acceleration was observed. With the increase of CHP and SFS concentration, the polymerization rate increased and the conversion was improved. In the redox initiator, EDTA can avoid Fe2+ oxidation to ferric hydroxide (Fe (OH) 3) and control the initial polymerization rate.2. High performance ASA resin was prepared in our study. It was found that there exist optimum values of the concentration of grafting agent, crosslinking agent, chain transfer agent TDDM and core/shell ratio to obtain the optimum mechanical property. Blending ASA grafting copolymer with different particle size with SAN resins prepare ASA resin. It was found that when the mixing proportion of particles with 90nm to particles with 695nm was 70/30, the impact strength of ASA resin can reach the maximum value and the synergistic effect could be found.3. The preparation and properties of PC/ASA blends were investigated. It was found that the rubber particle size had less influence on the tensile strength and processability, while it had great influence on the impact strength of PC/ASA blends. There exists an optimum particle size range of ASA graft copolymer to obtain high performance ASA resin. The PC/ASA can reach the maximum impact strength when the rubber particle size was about 160nm. The composition of PC/SAN has a great influence on the impact strength and melt flow rate of PC/ASA blend. We also found that the variation of AN content in SAN resin have litter influence on the morphology and mechanical properties of PC/ASA blends. The compatibilization caused by the introduction of compatibilizer SMA into PC/ASA blends can be found.4. The preparation and properties of PVC/ASA blends were investigated. High performance PVC/ASA blends were prepared by mixing ASA graft copolymer with PVC and SAN resin. It was found that there exists an optimum particle size range ASA graft copolymer to obtain high performance PVC/ ASA blends. The impact strength of PVC/ASA blend can reach 1250J/m when the particle size of ASA is 400nm. Combining particles with size of 72nm and 400nm into matrix, the synergistic effect can be observed. It was also found that the impact strength of PVC/ASA blends decreased with the increase of SAN content in matrix. However, the introductions of MSAN and PMMA into matrix have little influence on the mechanical properties of PVC/ASA blend.