ABSTRACT:The present paper deals with the mechanisms of photochlorination and thermal chlorination of polyethylene as influenced by the microtacticity evolution of the polymer under chlorination. The investigations have been carried out on a branched low-density polyethylene and a linear high-density polyethylene, both chlorinated under various conditions which enabled us to study the influences of the chlorination time, the chlorination temperature, the chlorination method, the solvents used, etc., on the mechanisms of chlorination. The high-resolution nuclear magnetic resonance analyses published elsewhere,5•6,12 the infrared spectroscopy,8 the ratios (Cl/C), and (number of CHCl units/number of CH2 units) and the degree of polymerization are the main results discussed.

ABSTRACT:A qualitative analysis of the infrared spectra of a series of photochlorinated (20°C) and thermally (90°C) chlorinated polyethylenes of various chlorine contents by weight (19% up to 73%) was made. In connection with microstructural high-resolution nuclear-magnetic-resonance studies published in our previous paper, 4 -6 new bands were identified between 500 cm-1 and 2000 cm-1• Changes in the molecular structure of the chlorinated polyethylene samples during the chlorination process were discussed.KEY WORDS Chlorinated Polyethylenes 1 Poly(vinyl chloride) I Poly(vinylidene chloride) I Band-Assignments I Conformational and Configurational Structures I

Dynamic mechanical and thermally stimulated depolarization current data have been obtained on polyethylene, γ‐irradiated in the molten state, as a function of irradiation dose. The β peak which appears in mechanical experiments has been attributed to motions of the chain backbone. The branches, like the crosslinks coming from γ‐irradiation, are fixed tie points for the chains.

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