Morphology build-up in dendritic hyperbranched polymer modified epoxy resins: modelling and characterization

The influence of cure temperature, composition and chemical structure on th e morphology resulting from chemically induced phase separation has been in vestigated for different epoxy functionalized dendritic hyperbranched polym ers blended with diglycydil bisphenol A and an aliphatic diamine. The cure temperature window chosen highlighted the influence of both the kinetics of phase separation and the thermodynamics of mixing on the final morphology. Tn relatively immiscible blends and at low cure temperatures, phase separa tion occurred immediately after mixing. However, increasing the miscibility by raising the temperature or modifying the chemistry of the dendritic hyp erbranched polymers resulted in a homogeneous mixture prior to cure, and at low modifier contents, cure induced phase separation was thought to be ass ociated with homogeneous nucleation of modifier rich spherical domains. Com plete suppression of the phase separation could be achieved combining the e ffects of modifier solubility and reaction kinetics, by increasing the cata lyst content in the most compatible blends. (C) 2000 Elsevier Science Ltd. All rights reserved.