Study On Two-step Solid Phase Grafting Modification Of Polypropylene With Multi-monomer

Modification of polypropylene(PP)with multi-monomer was studied by two methods.which were Supercritical CO2(SC CO2)assisted modification of polypropylene by solid-state and impregnation assisted modification of polypropylene by solid-state.The two methods have similar grafting mechanism,that's pre-swelling and thermal induced free radical grafting modification.Using azobisisobutyronitrile(AIBN)as initiator,methyl methacrylate(MMA)as comonomer,maleic anhydride(MAH)as the third monomer,acrylic acid(AA)was grafted onto PP in the solid state with assistant of SC CO2.The effects of swelling conditions,reaction conditions and feed of monomers on grafting reactions were discussed in details,and the results showed that grafting percentage and grafting efficiency can reach 4.29%and 71.5%respectively.The grafting products were characterized by FTIR,TG,SEM and water contact angle.FTIR confirmed that ternary-monomer had been grafted onto PP;Grafted PP has improved thermal stability and polarity;SEM showed that grafting process has achieved inner modification.Using AIBN as initiator,single monomer,bimonomer and ternary-monomer were grafted onto PP in the solid state with assistant of impregnant.The effects of impregnant species,impregnant dosage,swelling conditions,reaction conditions and feed of monomers on grafting reactions were investigated in details.Microstructure,melt behavior,and mechanics properties of grafted PP were studied by FTIR,DSC,tensile strength,elongation at break,MFR and SEM.Analysis results indicated that combination of soft monomer and hard monomer can counteract decreasing of mechanics properties caused by introducing side-chains.Grafting polar side chains decreased melting temperature and improved cooling temperature.After grafting,morphology of inner and surface of PP had been changed notable,and grafted molecules had been uniformly distributed in the PP substrate.