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Mechanism and kinetics of adiabatic anionic polymerization of ϵ‐caprolactam in the presence of various activators
Author(s) -
Kim Kap Jin,
Kim Yun Young,
Yoon Byung Sook,
Yoon Kee Jong
Publication year - 1995
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.1995.070571111
Subject(s) - polymerization , caprolactam , polymer chemistry , anionic addition polymerization , chemistry , branching (polymer chemistry) , bulk polymerization , chain growth polymerization , materials science , radical polymerization , organic chemistry , polymer
Nylon 6 was prepared by adiabatic anionic polymerization of ϵ‐caprolactam using hexamethylene dicarbamoyl dicaprolactam (HDC), cyclohexyl carbamoyl caprolactam (CCC), or phenyl carbamoyl caprolactam (PCC) as activators and sodium caprolactamate (NaCL) as a catalyst at various initial reaction temperatures ranging from 130 to 160°C. Adiabatic temperature rise was recorded as a function of polymerization time to investigate polymerization kinetics. Kinetic parameters for polymerization, which are more accurate than data reported to date, could be obtained by fitting the temperature rise data with a new polymerization kinetic equation involving crystallization exotherm and thermal conduction. The polymerization rate highly depended on the chemical structure of the activator used, which indicates that the initiating step where the activator is attacked nucleophilically by NaCL is a very important reaction step, affecting the overall polymerization rate. CCC showed the fastest polymerization rate, whereas HDC and PCC showed the medium and the slowest rate, respectively. The contributions of crystallization exotherm and thermal conduction to the resultant temperature rise during polymerization were significant, when the initial reaction temperature was lower than 140°C. In all cases, the molecular weight obtained from intrinsic viscosity measurement was greater than the expected molecular weight. This may be attributed to the branching and/or crosslinking reaction through Claisen‐type condensation reactions. © 1995 John Wiley & Sons, Inc.