Extended Chain Polymer Crystals

摘要

Linear polyethylene (LPE) and polymethylenepolyethylene copolymers were crystallized from melts under high pressure and then examined by means of differential thermal analysis, density determination, dilatometry, x-ray diffraction analysis (both wide and small angle), electron microscopy, and calorimitry. It is shown that (1) such polymers can be crystallized in the form of very thick lamellae having negligibly small surface energy effects; (2) molecular chains are fully extended in such lamellae; (3) the equilibrium m.p. of an infinite molecular weight LPE is 141.4C; (4) the lamellae can easily be superheated during melting; (5) the m.p. of lamella of LPE is not depressed by the introduction of up to 2 Me or Et side chains per 100 chain C atoms; (6) the formation of extended chain lamellae is hindered by the introduction of side chains.