Structural evaluation and thermal properties of poly(lactic acid) and different synthetic micas nanocomposites

Abstract

Two types of organophilic synthetic micas were used to prepare poly(lactic acid) (PLA) nanocomposites. The effect of both micas at different concentrations were evaluated and correlated to the nanocomposite structure and thermal properties. Nanocomposites containing 3, 5, and 7 wt% of mica were obtained by mixing the components in the melt state at different conditions of temperature, rotor speed, and contacting time. The mica Somasif MAE showed the higher affinity with PLA and caused a slight variation in the thermal properties. Nevertheless, the nanocomposite presented a lower-degradation temperature than the Somasif MPE alone. Despite no evidence of complete exfoliation, intercalation was noted in the composites obtained from the mica MAE. The organophilic mica Somasif MPE, which contains a high amount of intercalant, had a more significant influence on the composite properties, decreasing the Tg, and the crystallization temperature on heating, due to the plasticizing effect of the intercalant.