High Melt Strength Polypropylene

High melt strength polypropylene (HMSPP) has been studied since 1980s.Because of HMSPP's particular molecular structure ,superior properties and huge application potentials,the study on HMSPP has been a field of growing interest during the past two decades of years.Tn this work, we prepared a branched high melt strength polypropylene by using a peroxide initiator of lower decomposition temperature to modify propylene homopolymer in the oxygen-free environment .The long-branched polymer has superior rheological characteristics of stress hardening and higher melt strength than original PP. We investigated the effects of initiator contents,solvents ,reaction temperatures and time on the melt strength ang gel content of polymer. Our work will provide an option for preparing the high melt strength polypropylene.The molecular structure and properties of modified high melt strength polypropylene were studied with DSC,FTIR and NMR. The results indicated that the modified PP was a long-branched polymer with improved melt strength,higher crystallization temperature and rate and superior rheological characteristics. Hower,the lower branching density in the molecular structure made it difficult to detect the difference on FTIR and melt tensility.At last ,the study on mechanical properities and other related properities indicated that the polymer has outstanding mechanical properities and superior rheological characteristics and can be applied in the fields as thermo-forming and the manufacture of foams.