Castor-Oil –Modified Epoxy Resins As Model System Of Rubber – Modified Thermosets 2. Influence Of The Cure Conditions On Morphologies Generated.

ROXANA A. RUSECKAITE; LIJIAN HU; CARMEN C. RICCARDI; ROBERTO J.J.WILLIAMS

POLYMER INTERNATIONAL

Año: 1993 vol. 30 p. 287 - 295

0959-8103

Phase separation during polymerization was studied in a model system consisting of a diepoxide based on DGEBA, ethylenediamine and variable amounts of castor oil. Different events taking place during cure, i.e. phase separation, gelation and vitrification, are described in temperature versus time transformation diagrams (TTT), and conversion versus temperature phase diagrams. The concentration and average size of dispersed-phase particles followed opposite trends, i. e. one increased while the other decreased, when varying the castor oil concentration and the cure temperature this was explained gy assuming that the competition between nucleation and growth is determined by the viscosity of the could point. Low values of viscosity at the cloud point favour growth over nucleation while the opposite is observed for conditions leading to high values of viscosity.