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Dehydrochlorination of poly(vinyl chloride)
Author(s) -
Chang Eng Pi,
Salovey Ronald
Publication year - 1975
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760150808
Subject(s) - polyene , intramolecular force , steric effects , intermolecular force , vinyl chloride , raman spectroscopy , photochemistry , materials science , dipole , polymer chemistry , chemistry , molecule , stereochemistry , organic chemistry , physics , optics , copolymer , composite material , polymer
Abstract PVC has been dehydrochlorinated with alcoholic alkali in soution at 7°C for different lengths of time. At early stages of dehydrochlorination the dominant reaction is intramolecular removal of HCl and this gives rise to two intense Raman bands at ∼ 1126 (ν 1 ) and ∼ 1518 cm −1 (ν 2 ) and following UV irradiation, to a quadruplet ESR spectrum. Increasing polyene sequence length and intermolecular removal of HCl at later stages of reaction alters the quadruplet signal to a singlet, shifts ν 1 and ν 2 to lower frequencies and increases the molecular weight. The presence of polyene units stiffens the chain and increases the elastic modulus. The T g is, however, lowered slightly due to the removal of bulky chlorine atoms which relieves steric hindrance and dipole interaction between neighboring chains. The β‐transition is also rendered less distinct.