Study On The Synthesis Of High-Impact MIS Modifier And Its’ Properties

The higher field application of polyvinyl chloride(PVC)has been restricted because of its disadvantages,such as low heat resistance,bad toughness and processability.Therefore,the modification of PVC has been a fruitful way for the development of polymer materials.The optimum formulation and conditions of MIS(Methyl methacrylate-Isoprene-Styrene),the toughening effect of MIS resins on PVC and the microstructure and toughening mechanism were emphasized in this paper,and the specific contents are as follows:Isoprene(Ip)was firstly used as the main polymerization monomer and seeds emulsion polymerization was used to synthesize the large size particles with well-distribution.And then St and MMA monomers were separately grafted to PI latex particles.Graft copolymers of methyl methacrylate,isoprene and styrene monomers(MIS)with typical core-shell structure were synthesized.The MIS powder product,which was similar to PVC in performance density,particle size distribution and liquidity,could be obtained after a series of coagulation,centrifuging,filtering,washing and drying.Many experiment factors were secondly investigated,such as the solid content,the dosage of seed latex,the polymerization time,the content and composition of the rubber phase.The results show that the Tg(glass transition temperature)of the rubber phase reached-49℃ with 90wt%isoprene content in the rubber phase;the particle diameter decreased with the increasing seed amount,the particle size of the latex particles increased with the increasing solid content within a certain range.The mechanical properties,processability of the PVC/MIS blends and the morphology of the fracture surface were also studied.The impact result display the impact strength of the blends could reach 44.5kJ/m2 with 8wt%MIS content,70wt%rubber content,21%grafting ratio and 180nm particle diameter.SEM results show that the PVC/MIS system appears more obvious fibrous roots and cavitation.The mechanical properties of the system have been improved significantly after the addition of SEBS-g-MAH compatibilizer.The compatibility between the PVC matrix and rubber particles could be significantly improved and system appears ductile fracture after SEBS-g-MAH was added.The dynamic mechanical behavior of the blends was finally analyzed and the results show that the addition of MIS can reduce the system storage modulus and Tanδ.The storage modulus of the system could be reduced,and the flexibility of the molecular chain and the toughness could be improved with the addition of SEBS-g-MAH.