Investigation of relationship between crystallization kinetics and interfacial interactions in plasticized poly(lactic acid)/POSS nanocomposites: Effects of different POSS types

In this study, the correlation between crystallization behavior and interfacial chemistry of polyhedral oligomeric silsesquioxane (POSS)/poly(ethylene glycol) (PEG)-plasticized poly(lactic acid) (PLA) nanocomposites was investigated. Four different kinds of POSS particles having different chemical structures were used. The nanocomposites were melt compounded in a twin-screw microcompounder. Nonisothermal crystallization behavior of PLA/PEG/POSS nanocomposites was evaluated from common kinetic models such as Avrami, Avrami-Ozawa, and Kissinger. Besides, nucleating activity of the POSS particles was investigated in terms of Dobreva and Gutzow models. It was found that crystallization rate of PLA enhanced in the presence of POSS particles. Ozawa model was failed to describe the nonisothermal crystallization behavior of PLA/PEG/POSS nanocomposites. POSS particles introduced into the PLA/PEG matrix took the role of effective nucleating agents during crystallization. Activation energies of crystallization were evaluated by Kissinger and Takhor method. Polarized optical microscopy analysis showed that the spherulite nucleation density of PLA/PEG/POSS nanocomposites was much higher than that of the neat PLA. In order to investigate the interfacial interactions between POSS particles and plasticized PLA, thermodynamic work of adhesion approach was adopted using the experimentally determined surface energies. A strong correlation was obtained between interfacial chemistry and the nucleation rate in plasticized PLA/POSS nanocomposites. It was found that polar interactions were the dominating factor, which determines the nucleation activity of the POSS particles. POLYM. COMPOS., 39:2674-2684, 2018. (c) 2016 Society of Plastics Engineers