Poly(lactic acid)-based systems filled with talc microparticles: Thermal, structural, and morphological issues

Polylactic acid (PLA)-based composites containing 1, 3, and 5% by weight of talc microparticles were prepared by extrusion and characterized in terms of thermal, structural, and morphological issues. The binary materials were then compared with ternary systems including 5% by weight of a secondary poly(?-caprolactone) phase alongside with the several talc microparticles contents. The presence of talc brings significant increases of the PLA crystalline degree and reductions of PLA crystal sizes mainly in ternary systems, as shown by both calorimetric tests and wide angle x-ray diffraction measurements. Morphological investigations performed by scanning electron microscopy and polarized optical microscopy highlighted the reduction of the mean size of the PCL rich domain by increasing the talc concentration as well as the key role of PCL phase as assisting nucleation agent of the main PLA phase. Furthermore, indirect measurements by creep tests of the heat distortion temperature, have revealed increases of this parameter approximately equal to 110 and 175% with respect to the neat matrix for both binary and ternary compounds containing 3% by weight of talc.