MISCIBILITY AND CRYSTALLIZATION OF THERMOSETTING POLYMER BLENDS OF UNSATURATED POLYESTER RESIN AND POLY(EPSILON-CAPROLACTONE)

Poly(epsilon-caprolactone) (PCL) was found to be miscible with uncured polyester resin, i.e. oligoester (OER), as shown by the existence of a single glass transition temperature (T-g) in each blend. However, PC L was judged to be partially miscible with crosslinked polyester resin (PER) which was concluded from the results of thermal analysis. Fouri er-transform infrared (FT-i.r.) studies revealed that intermolecular h ydrogen bonding interaction between the components is an important dri ving force to the miscibility of PCL/OER blends and the partial miscib ility of crosslinked PCL/PER blends. The importance of entropy contrib ution to the miscibility of thermosetting polymer blends is also shown from the FT-i.r. results. The spherulitic morphology of the blends wa s remarkably affected by crosslinking. The birefringent spherulites we re observed in the uncured PCL/OER blends, whereas a distinct pattern of extinction rings, which was absent either in the pure PCL or in the uncured PCL/OER blends, was apparent in the crosslinked PCL/PER blend s. (C) 1998 Elsevier Science Ltd. All rights reserved.