Viscosity reduction and disentanglement in ultrahigh molecular weight polyethylene melt: Effect of blending with polypropylene and poly(ethylene glycol)

A significant reduction in melt viscosity of ultrahigh molecular weight polyethylene (UHMWPE) was obtained by blending with polypropylene (PP) and poly(ethylene glycol) (PEG). The mechanism of viscosity reduction was investigated from the view of disentanglement effect. Dynamic mechanical analysis indicated that the pseudoequilibrium modulus (E′) of UHMWPE/PP(80/20) blend in the rubbery plateau was much lower than that of UHMWPE. Accordingly, the calculated entanglement density (ν_e) of UHMWPE/PP (80/20) blend was smaller than that of UHMWPE. Further reduction in E′ and ν_e of the blend was obtained by the incorporation of 1 phr PEG. Slow DSC analysis showed that the high temperature endotherm and exotherm for UHMWPE at slow temperature ramp diminished and increased, respectively when 5 phr PEG was added. It also revealed that the entanglement level of UHMWPE decreased with the addition of a small amount of PEG.