The role of PB-1 on the long chain branching of PP by electron beam irradiation in solid state and melt viscoelastic behavior

In this study, a long-chain branched polypropylene (LCB PP) was prepared by electron beam irradiation in the presence of polybutene-1 (PB-1) and a trifunctional monomer, trimethylolpropane trimethacrylate (TMPTMA). The effect of PB-1 on branching is evaluated by measuring the viscoelastic behavior in shear and extensional mode of deformation. Long-chain branched structure showed prominent higher zero-shear viscosity (eta(o)) and storage modulus (G'), longer relaxation time and pronounced strain-hardening behaviors. It is found that 10 wt% of PB-1 resin in PP matrix increase the efficiency of branching process which can be due to the effect of PB-1 resin in facilitating the mobility of macro-radicals generated during irradiation. At higher percentages, due to the high tendency of PB-1 resin to beta-scission, the degradation reaction is more pronounced than its mobilizing effect in branching process. (c) 2013 Elsevier Ltd. All rights reserved.