Polylactic acid and poly(3-hydroxybutyrate) blends/ modified clay based Nano-biocomposites

DAVID A. D'AMICO; GRÉGORY STOCLET; VALÉRIE MIRI; LILIANA B. MANFREDI; VIVIANA P. CYRAS

Ciudad de Buenos Aires

Conferencia; 6th International Conference on Science and Technology of Composite Materials; 2015

Nowadays polymer blends are a suitable strategy to tune some polymers interesting properties. However, sometimes when a desired property is changed, another one can be deteriorated. It is well known that the addition of nanoclay can be used to improve the material global performance. Polylactic acid (PLA) and poly(3-hydroxybutyrate) (PHB) are two biocompatible and fully biodegradable polyesters that can be obtained from renewable sources. PHB is a thermoplastic with very similar characteristics to those of polypropylene, with good permeation properties to gases and water vapour and optimum reaction to ultraviolet light; but it is a fragile, crystalline and high melting point polymer. PLA has higher mechanical strength, is cheaper and easier to process than PHB. However, the use of PLA is limited because of its poor thermal barrier properties to moisture and oxygen as compared to the polymers from petroleum. In this work, PLA/PHB blends were processed by melt fusion in order to obtain a material with improved properties compared to those of the pure polymers. Moreover, nanocomposites of these blends were obtained by the addition of a modified clay. The resultant materials were characterized by differential scanning calorimetric analysis (DSC), transmission electron microscopy (TEM), small angle X ray scattering (SAXS) and mechanical test. By DSC analysis, two glass transition temperatures were found, indicating no miscibility between PHB and PLA. A good dispersion of nanoclay platelets was observed by TEM. Different blend composition micrographs showed that the platelets of clay are preferentially located in the PHB phase. SAXS analysis revealed an increase in the long period of PHB lamellas. The elastic modulus enhanced with increasing the proportion of PLA in the blend.