Study On Synthesis Of Low Molecular Weight SMA Copolymer By High Temperature Free Radical Polymerization

Styrene-maleic anhydride copolymer(SMA)is a functional polymer material,which can undergo saponification,esterification,amidation and etherification reactions,so SMA copolymer and its derivatives are widely used.According to its molecular weight,it is divided into two types: low molecular weight and high molecular weight.Compared with high molecular weight products,low molecular products are more widely used.Low molecular weight SMA copolymers are mainly synthesized by batch solution polymerization,and the molecular weight of the product is reduced by increasing the amount of initiator or chain transfer agent.Although the low molecular weight SMA copolymer product can be obtained by the above method,the use of too much initiator and chain transfer agent will make the polymerization reaction difficult to control,the product will have an unpleasant odor,and the product quality will be unstable.High temperature free radical polymerization is a commonly used polymerization method,which has the advantages of low solvent consumption,low system viscosity,polymer molecular weight can be adjusted by controlling the polymerization temperature,and the polymerization method is easy to achieve continuous production.In view of this,this paper carried out research on the synthesis of low molecular weight SMA copolymers by high temperature free radical polymerization in order to lay the foundation for its continuous polymerization.This paper has explored the feasibility of synthesizing low molecular weight SMA copolymer by high temperature radical polymerization,and studied the polymerization temperature,the amount of initiator,the amount of chain transfer agent,the ratio of monomers and the introduction of depolymerization monomer ?-methylstyrene(AMS)on the molecular weight,molecular weight distribution,copolymerization composition and thermal properties of SMA copolymer influences.And the polymerization conditions and formulations for the synthesis of low molecular weight SMA copolymers have been determined.The main research conclusions are as follows:(1)SMA copolymers with low molecular weight and narrow molecular weight distribution with molecular weights of 5000-18000 g/mol can be synthesized by high temperature radical polymerization.The optimal polymerization temperature is 200 ?.Under this polymerization temperature,the molecular weight of the copolymer can be adjusted by fine-tuning the amount of initiator or chain transfer agent.(2)The comonomer AMS has a strong regulation effect on the molecular weight of the SMA copolymer.By changing the ratio of AMS in the comonomer,a low molecular weight SMA copolymer with a molecular weight of 5000-11000 g/mol can be synthesized,and its molecular weight distribution is less than 1.8.In this ternary copolymerization system,the chain transfer agent tert-dodecyl mercaptan has little adjustment effect on the molecular weight of the copolymer.(3)The polymerization temperature is in the range of 170?200 ?.The copolymerization products of ?-methylstyrene and maleic anhydride are all low molecular weight products,whose molecular weight is less than 10000 g/mol and molecular weight distribution is less than 1.6.The polymerization conversion rate and copolymer molecular weight are mainly affected by the polymerization temperature,the amount of solvent and the ratio of monomers.(4)The SMA copolymer has good thermal and thermal oxidation stability.The introduction of AMS will reduce the thermal stability of the SMA copolymer,but it has no effect on its thermal oxidation stability.