Comparison of the effect of epoxy microspheres on the thermomechanical and rheological properties of an epoxy resin

The rheological and thermomechanical behaviors oftoughened epoxy resins filled with thermosetting microsizedspherical particles were investigated. Two epoxysystems were used to prepare microspheres: a BisphenolA-type resin (EPON825) cured with 2,4-diaminotolueneand a Bisphenol F-based epoxy resin (PY306)crosslinked with diethyltoluenediamine. Both systems ofmicrospheres were synthesized through dispersion polymerizationand differed to each other in size, as evidencedby morphological analysis. These microparticleswere blended, in different weight percents (10 and 20wt%), with a matrix consisting of diglycidyl ether of BisphenolA (EPON828) and 3,3-diaminodiphenylsulphone(3,3DDS). Rheological behavior of the prepared blendswas preliminarily studied. After cure, the dynamic-mechanicalproperties of the composites were also investigated.Results indicated that the reactivity of the uncuredblends, as well as the viscoelastic properties ofcrosslinked systems, are influenced not only by the natureand the amount of the microparticles introduced,but also, in a significant way, by their size.