Effect of Borax and Boric Acid on Thermal and Flammability Properties of Rice Husk Reinforced Recycled HDPE Composite

Abstract

Studies show Rice Husk (RH) and plastic appear viable in the production of a composite material. Flammability is a crucial parameter that limits multiple applications of such materials. Borax (BX) and Boric Acid (BA) have been used for wood and coating products, continually proving to be decent fire retardant agents in wood and plastic composites. In this study, the aim is to develop, test and investigate the thermal and flammability properties of RH reinforced Recycled High-Density Polyethylene (rHDPE) integrated with Maleic Anhydride Polyethylene (MAPE) as a binding agent, with Borax (BX) and Boric Acid (BA) as a fire retardant agent. RH was impregnated with BX and BA (1:1) solution at 2, 3, and 4% weight concentration and oven-dried after seven days at 105 °C for 24 hours. Only an average of 43 wt% of BX and BA remains after the impregnation process. Flammability test results show that adding RH to the composite enhanced flame retardancy compared to the pure rHDPE while adding MAPE as a binding agent makes the composite more flammable. Composite with BX and BA showed significant improvement in flame retardant properties by reducing the horizontal burning rate by 26% for 3% weight and 46% for 5% weight of MAPE. Thermogravimetric analyses exhibit an increase in the thermal stability by adding RH to reinforce rHDPE than pure rHDPE and further augmented by the integration of BX and BA. Keywords: rice husk, recycled high-density polyethylene, thermal, flammability