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The use of i.r. spectroscopy for gaining insight into the mechanism of stabilization of PVC by cadmium stearate

1988; Pergamon Press; Volume: 44; Issue: 12 Linguagem: Inglês

10.1016/0584-8539(88)80180-6

1873-3824

K. Volka, J. Škorvaga, Z. Vymazal,

Spectroscopy and Chemometric Analyses

Infrated spectra (1800-1500 cm−1) of polyvinyl chloride films stabilized with cadmium stearate, prepared by pressing at 180°C, are studied. The spectral changes are investigated in relation to the thermal treatment, interaction of cadmium stearate with water or with stearic acid, as well as to the degree of association of stearic acid in the polyvinyl chloride matrix. The fraction of cadmium stearate engaged in the reaction with the labile chlorine atoms of the PVC chain on a ca 7 min thermal treatment at 180°C, is estimated as approximately 2.4% of the initial stearate group content of the sample, which was 5 mmol/100 g PVC. As in PVC, the formation of stearic acid is found to be the dominant feature ofa model reaction of cadmium stearate with 4-chloro-2-nonene. It is concluded that if ester groups are formed, their concentration is too low for detection by i.r. spectroscopy, hence this technique is not able to give unambiguous evidence for the mechanism proposed.