Effect of gamma irradiation on tensile and thermal properties of poplar wood flour-linear low density polyethylene composites

Abstract

Poplar wood flour and linear low density polyethylene (LLDPE) composites were prepared by varying percentage of wood flour in LLDPE. The composites were synthesized via single screw extruder and then injection moulded to tensile test specimens. Maleic anhydride grafted LLDPE was used as a compatibilizer. The tensile and thermal properties of wood polymer composites were investigated to optimize the wood flour content into the polymer matrix. . The composite having 30% of wood flour in LLDPE (LPW3) was found to have the maximum tensile strength, almost double than for LLDPE. Its tensile modulus was also recorded as three times than that of LLDPE. The optimized composite (LPW3) was then subjected to gamma radiation of variable dose, ranging from 25 to 150 kGy. The tensile strength was found to be the maximum at 100 kGy with comparatively better tensile modulus. The onset degradation temperature of LLDPE is evaluated to be 442 °C and that of LPW3 before and after irradiation ranges from 421 to 433 °C. The activation energies of degradation, calculated by multiple heating rate kinetic methods of both non-radiated and radiated optimized composite were found to be relatively higher than that of LLDPE. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) techniques were also used in the present study.