Studies On The Synthesis Of High Performance ACR Impact Modifier And Its Modification For PVC

ACR is a kind of polymer with double layer or multi-layer Core-shell structure, which core is acrylate rubber and the shell always is the poly (Methyl -methacrylate). The types of ACR with the shell or the core cross-linking, the molecular chains through each other called LIPN.The technology of ACR has a rapid development since it was first prepared by Rohm&HaaS Company in 1960. ACR resin become the best modifier of PVC always used in outdoor and has aroused wide concern, becausewith an excellent tougheness, heat deformation-resistant properties, a wider processing temperature range and good weatherability. Since the main production technology of ACR resin and ACR 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 two difficulties in the preparation technology of ACR resin, there are, how to improve the strength between the two phase of ACR and the compatibility between ACR and the matrix of PVC. In order to solve this problem, three kinds of high performance ACR latex were synthesized by pre-emulsion multi-step seeded emulsion polymerization, which can realize the effective controlling of the particle size and cross-linking density, analyzed the mechanism of cross-linking density,the modification for PVC was studied. The toughening mechanism was researched, and the effect of synthetic parameters on the modification were discussed. The main research work are as follows: 1. According to the polymerization conditions which was selected, we synthesized three kinds of ACR by step seeded emulsion polymerization , three different ways were taken to combining two phase together and to improve the adhesion between them, according to the ways of that, called them as simple core-shell type, the transitional type and the cross-linking type (LIPN); realized the particle size controllable by exploring the relationship between the dosage of the seed and latex particle size of the PBA; studied difference between them through TEM, SEM, DSC and mechanical test, and found that LIPN -â… which was cross-linked by MAA has optimal performance.2.On the basis of LIPN-â… , introduced shell monomer and cross-linking agent into the core, and synthesized LIPN-â…¡with a controllable cross-linking density, which has copolymer in the core. And then tried to modified LIPN-â…¡by silane coupling agent.3,The control of cross-linking density was based on cooperate of the emulsifier SDS, AES and MAA, studied the mechanism of that MAA cross-linking by FT- IR, 1H-NMR,DSC methods.4.The preparation and properties of PVC/ACR blends were investigated. High performance PVC/ACR blends were prepared by mixing ACR copolymer with PVC. And the LIPN-â…¢modified PVC has the best impact strengh. The research on mechanism of ACR toughening PVC was carried by using SEM studied the dispersion of ACR in PVC matrix , and further researched the toughening mechanism, the results show that the plastic phase in the core of LIPN-â…¡can promote its dispersion in PVC.Investigation the factors of ACR it self on the influence of modified, it was found that the particle size of PBA and its contents had less influence on the tensile strength, while it had great influence on the impact strength of PVC/ACR blends. There exists an optimum particle size range to obtain high performance alloy. The PVC/LIPN-â… can reach the maximum impact strength 55.6KJ/m2 when the rubber particle size was about 200nm and the content of BA was about 65%; And we also found that in the range of 1.5%~2.7%, the increase of MAA dosage in Synthesis will promote blends impact performance improvement.For LIPN-â…¡, there exist optimum values of the core-shell ratio, rubber and plastic ratio and cross-linking density to obtain the optimum mechanical property. When the BA content was in the range of 40 ~ 50%, dosage of cross-linking agent was about 1.5%, gel. content was in 88 ~ 90%, PVC/LIPN-â…¡blends can be reach the maximum impact strength.The modification for LIPN-â…¡by silane coupling agent had little influence on the impact strength of PVC/LIPN, but some degree of improvement in heat deformation-resistant and processing can be observed.