Mechanical, morphological and thermal properties of hybrid kenaf fiber/nanoclay reinforced polylactic acid (PLA) biocomposite

Abstract

The biocomposites based on polylactic acid (PLA), short kenaf fiber and nanoclay hybrid is prepared through different processing method. The processes used are single and double compounding method using twin screw extruder followed by injection moulding. The mechanical properties of blended biocomposites are studied through tensile, flexural and impact tests. The morphology of the composites were characterized by scanning electron microscopy (SEM) and transmission electrom microscopy (TEM). The thermal properties are characterized by using differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and dynamic mechanical analysis (DMA). Besides these X-ray diffraction (XRD) and fourier transform infra-red (FTIR) analysis was carried out to know the nanoclay dispersion, percentage of crystallinity and possible bond formation. The aim of this work is to hybridize nanoclay and short kenaf fiber in polylactic acid (PLA) by using double extrusion method and followed by mechanical, thermal and morphological characterization. Mechanical properties show improvement with nanoclay, specifically impact strength increases more than 50% than unreinforced PLA. Double extruded hybrid biocomposite shows 3-10% better tensile and flexural properties than the single extruded. Similarly, addition of nanoclay increases decomposition and melting temperature (Tm) from 198 oC to 225 oC and 152 oC to 155 oC respectively. Crystallization temperature (Tc) is however decreases with nanoclay from 116 oC to 106 oC and storage modulus (E?) are increased by about 1GPa. These findings were also supported by scanning electron micrograph (SEM) and transmission electron micrograph (TEM) where in double extruded hybrid biocomposite better dispersion of nanoclay were observed. As for X-ray defraction (XRD) and Fourier transform infra-red (FTIR) spectroscopy, higher percentage of crystallinity and formation of new bonds respectively were seen with the addition of nanoclay, which indicates on enhancement in thermal and mechanical properties of PLA-based hybrid biocomposite.