Synthesis Of EPDM-g-MAS And PEB-g-MAS And Study Of Performance Of AEMS And ABMS

EPDM-g-MAS, synthesized by suspension grafting copolymerization of methylmethacrylate， acrylonitrile and styrene(MMA-AN-St) from ethylene-propylene dienemonomer(EPDM), was blended with styrene-acrylonitrile copolymer (SAN) to prepare a highimpact plastic AEMS. PEB-g-MAS, synthesized by suspension grafting copolymerization ofMMA-AN-St from Poly(ethene-co-1-butene)(PEB), was blended with SAN to prepare a highimpact plastic ABMS. AEMS and ABMS were characterized by excellent weatherability andyellow discoloration resistivity because of no double bond in molecule chain of polyolefinelastomer (ES): EPDM and PEB. AEMS and ABMS are potential engineering plastic, willsubstitute ABS if it can be in industrial production.The effect of Mooney viscosity of polyolefin elastomer, MMA/AN/St feeding weightratio, fES(fESwas equal to ES/(ES+MMA-AN-St)) and reaction time on the monomerconversion ratio (CR), average grafting ratio (GR), grafting efficiency (GE), rubber’s graftingratio(GRR), true grafting ratio(GRT) of copolymerization melt flow rate(MFR) and notchedimpact strength of AEMS or ABMS were investigated separately. The best syntheticconditions which made both MFR and notched impact strength of AEMS or ABMS to reachhigh level were obtained by optimizing grafting reaction condition.The components of EPDM/MMA-AN-St suspension grafting copolymerization wereseparated by different solvent and were qualitative/quantitative analysis by using Fouriertransform infrared spectroscopy (FTIR).The results showed when fEPDMwas50wt%, graftproduct were37wt%~43wt%, non-graft copolymer and non-graft rubber were22wt%~30wt%and28wt%~34wt%respectively, cross-linked product were3.45wt%. The non-graftcopolymer was increasing and non-graft rubber was deceasing with reaction time extending.It was found that the content of St in grafted chain and non-graft product were both higherthan that in the feeding monomers, AN were lower than that in the feeding, the content ofMMAin grafted chain were higher than that in non-graft product.DMA and TG/DTG showed that EPDM-g-MAS improved compatibility of SAN resinand EPDM, EPDM-g-MAS improved thermal stability of SAN. SEM analysis revealed thatthe impact fracture surface of AEMS appeared large and dense fibrous root morphology withmatrix occurring significant plastic deformation, toughing mechanism was highly shearyielding, and notched impact strength of AEMS was high. TEM analysis indicated that MFRof AEMS would be high when phases size of rubber and the distance between rubber particleslarge. Reducing the feeding ratio of St and increasing that of MMA would improve the dispersing morphology of EPDM phase in SAN resin, which could be good for MFR ofAEMS.The reaction mechanism of PEB/MMA-AN suspension grafting copolymerization wasstudied by analyzing the reaction behavior with different reaction time. It was found that thegrafting copolymerization mainly occurred in the earlier stage of reaction. The graftingcopolymerization basically stopped, remaining non-grafting copolymerization after60minute.There also exist chain scission and random regrafting of the backbone of PEB-g-MAN andnon-graft PEB which result in the production of multi-block polymer of PEB andPEB-g-MAN during the grafting copolymerization together with degradation of multi-blockpolymer. The possible reaction happened in product drying was studied. It was foundcyanoacrylate in graft chain reacted with cyanoacrylate in non-graft polymer, which resultedin GR rising. Cross linking reaction between graft PEB and non-graft PEB lead to GRRrising.Lots of gel came out in the early stage and decreasing with reaction time extending.SEManalysis showed as the reaction time extending, the toughing mechanism was cavitations withslight shear yielding at first, then becoming highly cavitations, craze with shear yielding, andfinally highly shear yielding.