Study of the Thermal, Mechanical and Melt Rheological Properties of Rice Straw Filled Poly (Butylene Succinate) Bio-composites Through Reactive Extrusion Process

The present study involved valorisation of rice straw (RS) in the form of rice straw flour (RSF) for the fabrication of poly (butylene succinate) (PBS) based bio-composites through a melt extrusion method, using dicumyl peroxide (DCP) as the cross-networking agent, and study of the morphological, thermal, mechanical and rheological behaviours of the extruded bio-composites. A layered like morphology with good dispersion of RSF in the PBS matrix was observed from X-ray diffraction and field emission scanning electron microscopic analysis. Thermo gravimetric analysis showed that the incorporation of RSF improved the thermal stability of PBS, whereas the value of the different thermal properties i.e. glass transition temperature (Tg), melting temperature (Tm) remained almost identical. Addition of DCP (2 wt%) into the PBS-RSF systems increased both the tensile strength and elongation at break (EB) (%) values. Rheological investigation of the bio-composites showed that the storage modulus (G') was less than the loss modulus (G") over the angular frequency (ω) range until crossover, corroborating the viscous behaviour of the samples. The complex viscosity, η' was constant when ω was less than 1 rad/s for all the samples, showing Newtonian characteristics. Shear thinning behaviour was observed when ω was greater than 1 rad/s. Furthermore, no phase separation was observed from the Han plot and good compatibility was noticed from the Cole–Cole plot, which signifies good rheological properties of the fabricated bio-composites.