Structure-properties correlations in poly(ε-caprolactone)/poly (styrene-co-acrylonitrile)/nanosilica mixtures: Interrelationship among phase behavior, morphology and non-isothermal crystallization kinetics

In this work, the effects of amorphous poly(styrene-co-acrylonitrile) (SAN) chains and hydrophilic and hydrophobic nanosilica at different loadings on the non-isothermal crystallization kinetics of PCL phase have been evaluated using different theoretical models including Avrami, modified Avrami, Ozawa and Mo equations. Using microscopic observations, the interrelations among the changes in the kinetics parameters and the morphology and phase behavior of PCL/SAN and PCL/SAN/nanosilica mixtures have been thoroughly investigated. Microscopic observations on the nanocomposites showed differences in the nanofiller dispersion and distribution state as well as preferential migration and localization state. These differences lead to contradictory trends in the effects of hydrophilic and hydrophobic nanosilica on the crystallization kinetics of pure PCL and PCL/SAN blends. The nanoparticle migration during non-isothermal DSC tests in PCL/SAN blends, the formation of nanoparticle agglomerates at higher loadings, the restrictions imposed on the molecular movements in the crystallization growth stage and slower phase separation and dissolution of PCL/SAN/silica mixtures result in the cooling rate dependence of the kinetics parameters.