Improvement of Physical, Mechanical and Thermal Properties of Okra Fiber/Polypropylene Composites by UV Radiation

Abstract

In this study, polypropylene (PP) composites (50% fiber by weight) were prepared by reinforcing lignocellulosic okra fiber using compression molding technique. In order to improve the mechanical properties of the composites, virgin okra fiber and PP sheet were exposed to different intensities of UV radiation (25–200 UV dose) and found significant enhancement in the mechanical properties up to 75 UV dose. Chemical structural and microstructural change of irradiated and non-irradiated composites was characterized by Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) was used to examine the change of the surface of okra fiber due to irradiation. Thermal stability of the composites was measured by the thermogravimetric analysis (TGA/DTG) and found to be in between PP and okra fiber. Thermal stability, melting temperature and crystallinity (%) of the composites further increased by UV radiation due to improved mechanical interlocking between irradiated okra fiber and PP. In addition, water uptake behavior of the composites was also performed and the irradiated composites showed a sharp decrease in the water absorption compared to that of the non-irradiated composites.