Morphology build-up in dendritic hyperbranched polymer modified epoxy resins: Modelling and characterisation

The influence of cure temperature, composition and chemical structure on the morphology resulting from chemically induced phase separation has been investigated for different epoxy functionalized dendritic hyperbranched polymers 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. In relatively immiscible blends and at low cure temperatures, phase separation occurred immediately after mixing. However, increasing the miscibility by raising the temperature or modifying the chemistry of the dendritic hyperbranched polymers resulted in a homogeneous mixture prior to cure, and at low modifier contents, cure induced phase separation was thought to be associated with homogeneous nucleation of modifier rich spherical domains. Complete suppression of the phase separation could be achieved combining the effects of modifier solubility and reaction kinetics, by increasing the catalyst content in the most compatible blends.