Hybrid green nanocomposites of poly(lactic acid) reinforced with banana fibre and nanoclay
Green nanocomposites of poly(lactic acid)/banana fibre/nanoclay were successfully prepared using melt blending technique followed by injection moulding. Untreated and chemically modified banana fibres and organically modified nanoclay (Cloisite 30B) were used as reinforcing agent within the poly(lactic acid) matrix. The banana fibres were subjected to various chemical modifications such as mercerization, silane treatment, sodium lauryl sulphate treatment, permanganate treatment and combination of mercerization and silane treatment. The biocomposites and bionanocomposites were subjected to characterization tests i.e. mechanical properties, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, heat deflection temperature (HDT) morphological properties using scanning electron microscopy and transmission electron microscope and water absorption studies to evaluate the effect of chemical modification of banana fibre and incorporation of nanoclay. Silane treated fibre reinforced poly(lactic acid) composites and its bionanocomposites displayed optimum tensile and flexural properties than that of virgin poly(lactic acid) resin, whereas the impact strength of composites showed a reverse order due to the brittle nature of matrix. Dynamic mechanical analysis result shows that the storage modulus of the bionanocomposites increases with respect to the virgin poly(lactic acid) and biocomposites. Differential scanning calorimetry results revealed that the glass transition was not significantly changed; however, the incorporation of both silane treated fibre and C30B nanoclay enhanced the nucleation of poly(lactic acid) crystallites as well as increased the melting temperatures. The results of thermogravimetric analysis depicted that fibre modification and incorporation of nanoclay can improve the degradation temperature of the composites. Scanning electron micrographs demonstrated improper dispersion of untreated fibres and proper dispersion of treated fibres within the poly(lactic acid) matrix, thereby revealing the interfacial adhesion between the fibres and matrix. Additionally, the composites were subjected to water absorption studies, which revealed that bionanocomposites exhibited better water resistance than biocomposites.