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Sur la dégradation thermique du polychlorure de vinyle. V. Stabilité thermique de polyméres semicristallins
Author(s) -
Guyot A.,
Bertet M.,
Tho Pham Quang
Publication year - 1968
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1968.070120404
Subject(s) - crystallinity , chlorine , thermal stability , melting point , catalysis , crystallization , condensation , polymerization , polymer chemistry , chemistry , polymer , inert gas , ionic bonding , chemical engineering , materials science , organic chemistry , ion , thermodynamics , physics , engineering , crystallography
The thermal dehydrochlorination of semicrystalline, but rather low molecular weight, PVC fractions, prepared by ionic polymerization catalyzed by tert ‐butylmagnesium chloride was studied under an inert atmosphere and compared with that of commercial polymer. When the samples are in powder form, the crystallinity of some fractions, which are insoluble at room temperature in all the usual solvents for PVC, induces a tremendous thermal stability, which is observed so long as the temperature is under the melting point of the sample. In dilute solution, the dehydrochlorination of all the samples is much slower, but the differences between the samples are less important; besides, a catalytic effect of some metallic impurities is observed. This catalytic effect is chiefly relative to a process of intermolecular condensation which causes the formation of a labile tertiary chlorine structure and so initiates or accelerates the purely thermal chain dehydrochlorination. It is suggested that, besides the crystallization and the catalytic effects, the configuration of the structural units could be an important factor in the course of the dehydrochlorination process.