| AES resin is a graft copolymer formed by grafting styrene(St)and acrylonitrile(AN)onto the molecular chain of ethylene propylene diene(EPDM).As an alternative to ABS resin,AES resin replace polybutadiene(PB)rubber containing double bonds with saturated EPDM.It not only has the same excellent mechanical properties as ABS resin,but also has weather resistance,anti-static and aging resistance.The synthesis of AES resin can be divided into blending method and grafting method.The blending method is simple to synthesize AES resin,but its performance is not as stable as the grafting method.Graft synthesis of AES resin is mainly emulsion polymerization and suspension polymerization.The emulsion polymerization method has a higher conversion rate and monomer utilization rate,but the inability to prepare EPDM latex in large quantities limits its application scope.The advantages of suspension polymerization are low polymerization temperature and easy to control the reaction process.The disadvantages are that monomer and EPDM rubber are difficult to dissolve and swelling in the aqueous phase,and the waste-water treatment capacity is relatively large.High temperature bulk synthesis of AES resin technology for its continuous production process,“low energy consumption”,“short flow”,“low cost”,“less waste”and other advantages will become a new generation of AES resin synthesis technology to be studied.However,due to the difficulty of ontology process technology,this technology is monopolized by large foreign enterprises at present,and has not been successfully developed in China.Therefore,it is necessary to study the synthesis of AES resin by high temperature bulk method.AES resin was synthesized by high temperature bulk method using ethylbenzene as solvent,tert-butyl benzoate peroxide as initiator and octytan as chain transfer agent.The effects of reaction conditions and experimental formula on the grafting rate of EPDM-g-SAN,molecular weight and distribution of free SAN resin,properties of AES resin and phase morphology were investigated.The feasibility of synthesis of AES resin by high temperature bulk polymerization was investigated,and the composition and reaction conditions affecting the synthesis of AES resin by high temperature bulk polymerization were clarified.The main research conclusions are as follows:(1)AES resin with impact strength of 30～50 k J/m~2 and tensile strength of 20～40 MPa can be synthesized by high temperature bulk polymerization.(2)The grafting rate of AES resin synthesized by high temperature bulk method was affected by reaction conditions and experimental formula,and the dosage of initiator and chain transfer agent was the most important factor.When initiator dosage is 0.2%chain transfer agent dosage is 0.1wt%.The graft rate of the synthesized polymer can reach 30%and the molecular weight can reach 8.5×10~4.(3)The graft rate of polymer and the shape of rubber phase are the direct factors affecting the mechanical properties of AES resin synthesized by high temperature bulk method.When the graft rate reaches more than 25%,the impact strength of AES resin synthesized can reach more than 35 k J/m~2.The best performance of AES resin was obtained when the rubber particle size was large and the internal inclusion structure existed.(4)The phase morphology of AES resin synthesized by high temperature bulk method is affected by reaction conditions and formula composition.The stirring rate has the greatest influence on the phase morphology,and the optimal stirring rate is 200 rpm,where the rubber phase has a bimodal distribution and an internal inclusion structure. |
