Chlorinated Polyethylene. I. Infrared Study

Abstract

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

Chlorinated Polyethylene. II. Mechanisms of Chlorination

“…This Svalues' decrease (Table V) means an absorbance decrease of the PVC syndiotactic sequences, 8 which indicates that the PVC syndiotactic sequences are chlorinated preferentially v.s., the PVC isotactic sequences through the two mechanisms described below:…”

“…Following these various CPE studies it is possible to investigate the photochlorination and thermal-chlorination mechanisms of polyethylene. The results obtained with PVC, 2 -4 infrared, 8 and NMR analyses 2 -4 of the CPE samples will be sound bases on which to discuss the chlorination mechanisms proposed.…”

“…We think that the fundamental parameters linked to the chlorination energy could be the conformational and configurational changes occuring in the chlorinated polymer chains. 8 Table IV lists the structures which can be detected 5 ' 6 ' 12 by high-resolution NMR analyses in the CPE samples' chains, for different chlorine contents and chlorination methods.…”

“…Owing to the high yield, Y-%, of the chlorination operations (Table V) the Mn increase cannot be attributed to a fractionation of the CPE samples during their recovery from the chlorination mixture. 8 It is important to notice that the initial chain-breakages take place whatever may be the parent-polymer, which indicates that the branching points are not specially concerned. Second Region: 56-61-% to 73-% Chlorine Content.…”

“…From the 56-% up to the 64-% chlorine content value, for thermal CPE samples produced from the linear polyethylene, and from the 60.5-% up to the 68.4-% chlorine content value, for photochlorinated CPE samples, the increase of the syndiotacticity index, S, 8 is enhanced (Table V), which means an absorbance increase of the PVC syndiotactic sequences present in the chlorinated polymeric chains. 8 This absorbance increase cannot be attributed to the appearance of new PVC syndiotactic sequences (a) Radical substitution.…”