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Bulk anionic copolymerization of ε‐caprolactam in the presence of macroactivators derived from polypropylene glycol
Author(s) -
Chen Yun,
Chen ShowAn
Publication year - 1993
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.1993.070471002
Subject(s) - caprolactam , isocyanate , polymer chemistry , polypropylene glycol , copolymer , prepolymer , polypropylene , viscosity , chemistry , melting temperature , intrinsic viscosity , enthalpy , materials science , polyurethane , organic chemistry , polymer , composite material , thermodynamics , physics , polyethylene glycol
Bulk anionic copolymerization of ε‐caprolactam (CPL) was conducted, under four different conditions by changing temperature (110 or 125°C) and [NCO]/[NaH] ratio (1, 2, or 3), in the presence of NCO‐terminated polypropylene glycol (P1) and its CPL‐blocked prepolymer (P2). Under the same conditions and reaction time, the conversion of CPL and reduced viscosity of the P2 system were higher than those of the P1 system. However, at the same conversion the P1 system showed higher viscosity for reactions at 125°C with [NCO]/[NaH] = 3 and at 110°C with [NCO]/[NaH] = 2. These results were attributed to cyclotrimerization of NCO groups of P1 (formation of isocyanurate) at the initial stage, which not only consumed the effective concentration of NCO but also increased the viscosity of the P1 system. Comparing IR spectra of the reaction products of model compounds, phenyl isocyanate and CPL‐blocked phenyl isocyanate, with NaH/CPL also supported this conclusion. The crystalline melting temperature ( T m = 198–208°C) and melting enthalpy of the final products depended on the conversion of CPL and the types of macroactivators. © 1993 John Wiley & Sons, Inc.