Mechanical properties and thermal stability of poly(L-lactide)/calcium carbonate composites

Poly(L-lactide) (PLA) was melt-mixed with micrometer-sized and nanosized calcium carbonate (CaCO3) particles before and after modification with calcium stearate. Adhesion between the CaCO3 particles and the PLA matrix was assessed qualitatively by scanning electron microscopy observation of the fractured surface morphology of the composites. The effect of the incorporation of the CaCO3 particles on the thermal stability of the PLA-based composites was quantified by the temperatures corresponding to 5 and 50% of weight loss and the activation energy determined through thermogravimetric analyses of the composites. The tensile strength and modulus values of the composite were improved greatly without a significant loss in the elongation at break when the nanosized CaCO3 was incorporated up to 30 wt %. (c) 2008 Wiley Periodicals, Inc.