Study On Reaction Kinetics Of ACS Resin Synthesized By High Temperature Bulk Polymerization

ACS resin is synthesized by the graft copolymerization of styrene(St)and acrylonitrile(AN)onto CPE chain.It can be produced by the blending or grafting process.In comparison,the ACS prepared by the grafting method is of better and more stable performance.Theoretically,the ACS resin,produced by grafting method,can be prepared by anyone of emulsion,suspension,solution or bulk polymerization.Industrially,it is produced by an aqueous suspension polymerization technology.Its advantages are the lower polymerization temperature,easy removal of polymerization heat and easy control of the process.The disadvantages are the longer swelling time,intermittent operation,unstable product quality and complicated post-treatment.The biggest problem of aqueous suspension polymerization is that the larger amount of waste is discharged and needs to be treated.The continuous bulk polymerization process,which has the advantages of continuous production,process simple,lower energy consumption,lower cost,lower waste,saving energy and environmental protection,has become a new generation of ACS resin synthesis technology that has been developed by domestic and foreign companies.The bulk polymerization reaction of ACS resin is very complex,which include not only the copolymerization of styrene and acrylonitrile but also the graft copolymerization of styrene,acrylonitrile and rubber CPE.The performance of ACS resin prepared by the above method is affected by the molecular weight of SAN resin and the graft ratio of ACS grafting copolymer.Therefore,it is necessary to investigate the bulk polymerization reaction kinetics of ACS,the effects of various polymerization and formulation factors on the copolymerization reaction rate,the molecular weight and distribution of SAN resin and the grafting rate for preparing the resin with excellent performance.The bulk polymerization reaction kinetics of ACS resin was studied with toluene as diluent,ditertbutyl peroxide as initiator and tert-dodecyl mercaptan as chain transfer agent.The effects of the polymerization temperature,St/AN monomer ratio,amount of diluent,initiator,chain transfer agent and initiation on the polymerization rate,grafting rate,molecular weight and distribution of SAN resin were investigated.The polymerization and ingredient factors,affecting the bulk polymerization reaction kinetics,the grafting rate of ACS graft copolymer,the molecular weight and its distribution of SAN,were cleared.Meanwhile,the effect of heat self-initiation on the bulk polymerization reaction kinetics,the structure and performance of ACS resins were clarified.The main results are as follows:1)The polymerization temperature,St/AN ratio and diluent amount have great influence on the polymerization rate of high temperature bulk polymerization of ACS resin.The polymerization rate can be increased by increasing the polymerization temperature,proportion of AN in the copolymerization monomer or reducing the amount of diluent 2)The content of initiator and chain transfer agent is the main factor affecting the molecular weight of free SAN.The reaction conditions and St/AN monomer ratio have little effect on it.3)During the high temperature bulk polymerization of ACS resin,the grafting reaction is always carried out.As the conversion of monomer is less than 80%,the grafting reaction is conducted at a faster polymerization rate,and then gradually slowing down.4)The ACS resin can be synthesized by the thermal self-imitating high temperature bulk polymerization of styrene,the polymerization rate of which is slower than that initiated by initiator(DTBP).The ACS resin with an impact strength of 42.6 k J/m2 can be prepared by this way but it needs a longer reaction time...