Complex adhesion effects of inorganic nanofillers vs microfillers in polymer composites

The adhesion parameters of fillers in composites, coefficient of wetting, interfacial free energy and work of adhesion, were calculated in order to evaluate the difference between the effects of selected microfillers vs nanofillers in polyacrylate (PA) and poly (vinyl acetate)(PVAc) matrix. The results showed that the improved fundamental adhesion, i.e. higher work of adhesion in nanocomposites resulted in the improved practical adhesion i.e. higher mechanical properties. The interfacial region was additionally modified by the controlled pre-treatment of calcium carbonate micro- and nanofillers by sodium stearate that lowered the interactions with PVAc matrix. The composite morphological and mechanical properties changed accordingly. The lowered coefficient of interactions explained the pronounced composite failure at the interphase by dewetting and finally lead to the composite weakening. The conclusion about the complex relationship between the composite properties and engineering the interphase was confirmed.