Characterization of Compatibilizing Effect of Organoclay in Poly(lactic acid) and Natural Rubber Blends by FT-Rheology

Abstract

The compatibilizing effect of organoclay in immiscible poly(lactic acid) (PLA) and natural rubber (NR) blends was investigated through small-amplitude oscillatory shear (SAOS) and large-amplitude oscillatory shear (LAOS) tests by varying clay concentrations, mixing conditions, and types of clay. A quantified nonlinear parameter (I3/1) from FT-rheology and complex moduli (|G*|) were used to analyze the structural development of the PLA/NR blends in response to added clays. The nonlinear–linear viscoelastic ratio (NLR ≡ normalized nonlinear viscoelastic property/normalized linear viscoelastic property) was also introduced to describe morphological changes in the blends. Observation of the TEM images revealed that the drop size of natural rubber decreased as the clay content increased from 0.5 to 3 wt %. However, the NR size did not change above 3 wt % of the clay. The NLR value increased up to 3 wt % and then reached a plateau. The drop size reduction due to increased mixing rates was reflected in the NLR v...