Manufacturing and characterization of highly environmentally-friendly composites with polylactide matrix and mango kernel seed flour

Abstract

This work reports on the development of polylactide (PLA)/mango kernel seed flour (MKSF) composites combined with tributyrin (TBN) and triacetin (TCN) as plasticizers. Thus, wood plastic composites (WPC) are obtained by extrusion and injection-molding processes. The solubility, mechanical, morphological, thermal, colorimetric, water absorbance, flowability, and disintegrability properties are evaluated. The ductility of the PLA+MKSF composite is improved by the plasticizing effect of TBN and TCN (10 phr (parts per hundred resin) each). Elongation at break is increased from 4.4 up to 9.5 and 8.3%, respectively. The theoretical solubility analysis supports the good miscibility between PLA with TBN and TCN (relative energy difference (RED) values of 0.86 and 0.73, respectively) deduced from the mechanical performance. Field emission scanning electron microscopy (FESEM) images also corroborate the mechanical findings, where a decrease in the presence of voids in the PLA matrix suggests certain compatibility between MKSF and TBN, and TCN. Differential scanning calorimetry (DSC) and dynamic-mechanical-thermal analysis (DMTA) results show that the plasticizers decrease the glass transition temperature and the melting temperature of PLA, thus improving its ductility. Thermogravimetric analysis (TGA) results indicate that the thermal stability of the composite is slightly decreased due to the relatively high volatility of the plasticizers, while MKSF does not affect this matter. The composites exhibit excellent biodegradability, presenting more than 90% of disintegration in compost soil conditions in 12 weeks. Finally, MKSF provided the composites with a wood-like dark brown color and with high water absorbance.

Keywords

• polymer composites
• biodegradable polymers
• mechanical properties
• thermal properties
• plasticizer