Synthesis and characterization of PLA nanocomposites containing nanosilica modified with different organosilanes II: Effect of the organosilanes on the properties of nanocomposites: Thermal characterization

Thermal behavior of polylactic acid (PLA)/nanosilica nanocomposites prepared via bulk ring opening polymerization from lactide was investigated by differential scanning calorimetry and thermogravimetric analysis (TGA). Both unmodified nanosilica and modified by surface treatments with different amounts of two distinct silanes were used. Samples containing pure silica show enhanced crystallization processes; with silane-modified silica this effect is magnified, especially in the case of materials with high loadings of epoxy silane. Nonisothermal crystallization temperatures become higher and isothermal crystallization kinetics show a marked increase of Kinetic constant (Kc). TGA analyses show that, when pure nanosilica is present, nanocomposites have a thermal stability far greater than the one of standard PLA, starting their degradation at temperatures up to 70 � C higher than the ones of pure PLA. When silanes are present, thermal stability lowers as silane content increases, but it is anyway higher than the one of the pure polymer. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 3057-3063, 2013