Properties and structures of polylactide filled with poly(e-caprolactone)-coated calcium carbonate

The poly(e-caprolactone) (PCL)-coated microsized calcium carbonate (CaCO3) was prepared by high-speed hybrid mechanical coating. Polylactide (PLA) was melt-blended with neat and modified CaCO3 particles. Phase morphology, microstructure, and thermal dynamic rheological and mechanical properties of the composites were investigated. Differential scanning calorimetry reveals that the addition of coated CaCO3 remarkably makes the cold crystallization temperature decrease but has little influence on the final degree of crystallinity of PLA. Dynamic rheological tests indicate that complex viscosity and loss modulus of modified CaCO3 system are lower than those of neat CaCO3 system. Scanning electron microscopic results show that the coated CaCO3 microparticles disperse more uniformly in the PLA matrix compared with neat particles. The smooth and round coated particles promote the dispersion of CaCO3 particles in the PLA matrix, and PCL enhances the interfacial adhesion between CaCO3 particles and the PLA matrix. From mechanical tests, it is found that toughness of the composites is greatly improved by the incorporation of PCL-coated CaCO3 microparticles. It is glad to see that the elongation at break of the composite with 15 phr coated CaCO3 is as high as 310%. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012