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Phase separation during fast (RIM) poly‐urethane polymerization
Author(s) -
Yang Wenliang P.,
Macosko Christopher W.
Publication year - 1989
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19890250104
Subject(s) - isocyanate , materials science , dynamic mechanical analysis , rheometry , polyurethane , rheology , phase (matter) , polymer chemistry , absorbance , elastomer , chemical engineering , rheometer , isothermal process , composite material , polymer , thermodynamics , chemistry , organic chemistry , chromatography , engineering , physics
Phase separation dynamics during a reaction injection molding process of an elastomeric polyurethane was studied via FT‐IR and rheology. 4, 4′ methylenediphenyl isocyanate and 1, 4 butanediol were mixed with 50 wt% of a 2000 molecular weight poly(proplyene oxide)polyol catalyzed by dibutyltin dilaurate. A small reaction injection molding machine was used to impingement mix the chemicals and inject these directly into a Fourier transform infrared spectrometer or into a rheometer. The reaction conversion was followed by the isocyanate absorbance and the development of inter‐urethane hydrogen bonding was related to phase separation dynamics. Isothermal dynamic mechanical modulus build‐up during reaction was monitored by a thin gap parallel plate geometry subjected to small amplitude oscillation. An optimum reaction temperature was found, below which phase separation prematurely cuts off high molecular weight build up. Above this temperature phase separation is too slow and incomplete; modulus values are lower. Increasing catalyst reduces this optimum temperature.