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Char formation in polyvinyl chloride. III. Mechanistic aspects of isothermal degradation of PVC containing some dehydrochlorination/charring agents
Author(s) -
Brauman Sharon K.
Publication year - 1981
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.1981.070260131
Subject(s) - charring , char , polyvinyl chloride , pyrolysis , zinc , chemistry , isothermal process , degradation (telecommunications) , polymer chemistry , chemical engineering , organic chemistry , telecommunications , physics , computer science , thermodynamics , engineering
We pyrolyzed PVC with and without the char‐promoters iron (III) pyromellitate, zinc pyromellitate, and MoO 3 (1 phr) under isothermal conditions (207°C, nitrogen) and analyzed the soluble and insoluble residues to characterize the reactions important to charring. Both pyromellitates, apparently acting as their metal chlorides, catalyze dehydrochlorination and crosslinking that could lead to rapid charring; however, the zinc additive also catalyzes undesirable fragmentation. MoO 3 , possibly acting as an oxychloride, has only a small effect on PVC degradation under the conditions used; however, it does suppress fragmentation. The relative rates of crosslinking to fragmentation are important in determining char yields.