Structure of the crystalline phase in gelled polyethylene and its effect on the orientational ability of gel fibers

Abstract

The crystalline phase of gelled ultrahigh molecular weight polyethylene derived from reactor powders with different synthetic prehistories is studied by means of low frequency Raman spectroscopy and small angle X ray scattering. The results obtained suggest that the gels contain folded crystallites 3-6 nm in size that, in some samples, form stacks of two or more units bound by common straightened segments of mac romolecules (double folds). The gels are used to prepare highly oriented polyfilament fibers, and the strengths and Young moduli of the fibers are estimated. The gels containing stacks of crystallites demonstrate better ability to form high strength fibers during hot drawing than the gels containing individual crystallites. The effect of the strength of junctions in the polymer spatial network of the gels on the attainment of optimum mechanical properties of the drawn fibers is discussed.