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 (η0) 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 β-scission, the degradation reaction is more pronounced than its mobilizing effect in branching process.

► The effect of PB-1 in branching of PP by electron beam irradiation is studied.
► PB-1 promoted long chain branching of PP in solid state.
► Using 10 wt% PB-1 in PP matrix increased the branching efficiency as a mobilizer.
► At 20 wt% of PB-1 the degradation reactions were dominated to branching process.