Dehydrochlorination of poly(vinyl chloride)

Abstract

AbstractPVC 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 (ν1) and ∼ 1518 cm−1 (ν2) 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 ν1 and ν2 to lower frequencies and increases the molecular weight. The presence of polyene units stiffens the chain and increases the elastic modulus. The Tg 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.