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Reaction‐induced phase separation during the formation of a polyurethane‐unsaturated polyester interpenetrating polymer network
Author(s) -
Chou Y. C.,
Lee L. J.
Publication year - 1994
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760341603
Subject(s) - materials science , polyurethane , differential scanning calorimetry , coalescence (physics) , interpenetrating polymer network , spinodal decomposition , phase (matter) , polymer , scanning electron microscope , transmission electron microscopy , chemical engineering , polyester , polymer chemistry , composite material , organic chemistry , thermodynamics , nanotechnology , chemistry , physics , astrobiology , engineering
In this study, an interpenetrating polymer network (IPN) based on a polyurethane (PU) and a partially end‐capped unsaturated polyester (UPE) was prepared. The reaction‐induced phase separation process of the IPN was studied using a phase contrast optical microscope and a transmission electron microscope (TEM), while reaction kinetics and onset of gelation were determined by a differential scanning calorimeter and a rheometer respectively. Except at low temperatures, the phase separation patterns were found to follow the spinodal decomposition mechanism. An interconnected phase developed quickly and was followed by coalescence of the periodic phase to form droplet/matrix type of morphology. A second level of phase separation also occurred within both the droplet and the matrix phases in some cases. The domain sizes resulting from both levels of phase separation gradually increased until the structure was locked by chemical gelation. Reaction temperature, PU reaction rate, and UPE reaction rate all had significant effects on the final morphology of the formed IPNs.