Oriented crystallization of biphenyl in low-density polyethylene with a single texture

Doubly oriented specimens with a single texture can be obtained by unidirectional rolling of a sheet of low-density polyethylene. Swelling of the oriented samples with liquid biphenyl and in situ crystallization of the biphenyl give indirect information about the morphology of the polymer. In such samples, annealed a few degrees below the melting temperature, the orientation of the biphenyl crystals is a consequence of the interaction of the two crystalline lattices. The (001) biphenyl planes are parallel to the (h01) limiting planes of the lamellar polymer crystals. Theoretical considerations show that the epitaxial conditions are best fulfilled when the limiting planes of the lamellas are parallel to (201) planes. The experimental value of h is 3.