Gk. Elyashevich et al., CHANGES IN THE AMORPHOUS PHASE OF POLYETHYLENE UPON HIGH EXTENSION, International journal of polymeric materials, 22(1-4), 1993, pp. 191-199
The structure of noncrystalline regions of HDPE oriented filaments pre
pared by two different techniques with various degrees of orientation
lambda has been studied by density measurements, small-angle X-ray sca
ttering and DTA. It is shown that at lambda > 10 the noncrystalline re
gions of the oriented structure prepared from a crystallized material
have 80 nm voids (pores) in addition to an amorphous phase. The volume
fraction of pores grows with increasing lambda. If a sample is prepar
ed by crystallization from a pre-oriented melt, it does not contain di
scontinuities, and its noncrystalline regions consist of the amorphous
material alone. In this case the density of the amorphous phase does
not depend on the degree of sample orientation and has a constant magn
itude typical of highly oriented PE samples.