NMR studies of chlorinated poly(vinyl chloride) and polybutadiene

Abstract

Molecular structures of chlorinated poly(vinyl chloride) and polybutadiene have been studied by high resolution NMR. The spectra of the chlorinated polymers give broad signals. New peaks appear in the lower fields of the CH2 and CHCl groups with increasing chlorine content. The chlorination of poly(vinyl chloride) takes place predominantly on CH2 rather than on CHCl, e.g., a 70% chlorinated polymer has about 10 mole‐% of CCl2 groups. Polybutadiene reacts first with chlorine by addition to give a head‐to‐head poly(vinyl chloride), and then the substitution of the hydrogen atom takes place. Chlorinated polybutadiene with 70% Cl has about 18 mole‐% of CCl2. The multiplets characteristic of spin‐spin couplings in the spectrum of the original poly(vinyl chloride) are still observed in that of the highly chlorinated product. This fact shows that a considerable number of poly(vinyl chloride) sequences of certain lengths persist in the highly chlorinated polymer.

Blends of Chlorinated and Normal PVC

“…According to the most recent studies carried out with infrared (5,8,22) and NMR techniques (13,18,19), these differences are not justified by the determination of the struc ture, in terms of the ratio between 1.2 and 1.1 dichloroethylene units.…”

Some aspects regarding the structure and the mechanism of the PVC synthesis

“…The internal double bond could appear through another process as the copolymerization with acetylenic impurities [ 1 11 (as we have demonstrated), by an after-polymerization process [ 161 of the unsaturated end groups, or by dehydrochlorination. That a hydrogen atom is extracted from the -CH2-group in PVC through a radical mechanism was demonstrated by other authors [23]. As a result of this process, a radical with structure (9) is formed.…”

High-Resolution NMR Study of Chlorinated Polyethylenes

“…And those of vinylchloride-ethylene copolymers (VC-Et) have been studied by Misono, eta!., 11 Schaefer,12 and Wilkes, et al 13 As for substituted polymers, the structure of chlorinated poly(vinyl chloride )(ClPVC) and chlorinated poly(butadiene )(ClPBD) have been studied by Sobajima, et a/. 14 Petersen and and Tho, et al/ 6 have also studied the structure of ClPVC. Svegliado, et al/ 7 have in particular studied chlorine distribution of ClPVC and determined the sequence length of vicinaldichloride units.…”

“…These chemical shifts can be attributed not In addition to the above interpretations the absorption peak centered near 5.30 ppm was also observed in the NMR spectra of CIPBD and the intensity of this peak increased with the increase of chlorine content. 14…”

“…where, Si is the area under the chemical shift and a, b, g are mol % of the methylenes or methynes in the pentads and c, d, e, fare those in the triads as listed in Table II. Sa has the following meaning (14) The mol % of CH2, CHCl and CC12 units can now be obtained from the assignments as follows…”