Crystalline properties of poly(L-lactic acid) composites filled with nanometer calcium carbonate

The poly(L-lactic acid) (PLLA) filled with nanometer calcium carbonate (nano-CaCO3) composites were prepared by means of a twin-screw extruder in the present paper. The nano-CaCO3 surface was treated with stearate. The crystalline properties of PLLA/nano-CaCO3 composites were measured using a differential scanning calorimeter, to identify the influence of the nanometer particle content on the crystalline properties. The results showed that the crystallization onset temperature, crystallization temperature and crystallization end temperature as well as the crystalline degree of the composites were obvious higher than those of the unfilled PLLA resin when the particle weight fraction (phi(f)) was 1%, then they varied slightly. While the crystallization temperature interval decreased slightly. The improvement of crystallinity degree might be attributed to the heterogeneous nucleation of the nano-CaCO3 in the matrix. (c) 2012 Elsevier Ltd. All rights reserved.