A SANS STUDY OF THE PLASTIC-DEFORMATION MECHANISM IN POLYETHYLENE

Small angle neutron scattering was used to investigate the role of partial melting and recrystallization in the solid state deformation of polyethylene. Blends containing 4 vol% deuteropolyethylene in protonated polyethylene were deformed in a pure shear mode. The scattering cross section of the undeformed blends was well in excess of that expected for randomly (statistically) dispersed molecules, due to isotopic segregation effects between the deuterated and the protonated species. A significant reduction in the excess scattering was observed as the blends were deformed beyond the yield point. Upon further deformation, the cross section underwent a further modest decrease. Such a reduction is known to occur on melting. The neutron scattering results, hence, support the notion of local melting during the yielding and the subsequent deformation processes.