Macromolecules, Vol.44, No.12, 5053-5063, 2011
Synthesis and Characterization of Novel Ethylene-graft-Ethylene/Propylene Copolymers
A sequential metallocene-catalyzed synthesis of ethylene/propylene macromers, which are subsequently incorporated into growing polyethylene chains, leads to comb-like polymers. After the synthesis, a Soxhlet extraction ensures the purity of the sample. The GPC-MALLS analysis reveals narrowly distributed samples with a non-negligible degree of branching. The comb polymers show a very high viscosity, which significantly differs from conventional long-chain branched metallocene polyethylenes (LCB-mPE) but is in agreement with findings on comb model polymers. The zeroshear rate viscosity eta(o) lies significantly above the relation between M(w) and eta(o) for linear and for conventional LCB-mPE. The thermorheological behavior is complex and differs from that observed for LCB-mPE but also does not resemble an LDPE-like thermorheological behavior.