Effect of ammonium polyphosphate as synergist with nano silica dioxide on flammability of boron compound pretreated bamboo flour-HDPE composite

Abstract

In this study, bamboo polymer composite (BPC) was prepared by blending of high-density polyethylene (HDPE) with boric acid - borax (Ba-Bx) pre-treated bamboo fibers as reinforcement material and by using maleic anhydride grafted polyethylene as coupling agent. BPCs were incorporated with conventional flame retardants (FRs) additives such as ammonium polyphosphate (APP) along with nano particles such as silicon dioxide (nano-SiO2) and flame performance was investigated using cone calorimeter and limiting oxygen index analysis (LOI). The thermal behaviour of BPC was investigated under nitrogen atmosphere using thermogravimetric analyser (TGA). The maximum improvement in flammability was achieved with flame additive i.e., Ba-Bx 5%/APP15%. LOI value was found to be highest at Ba-Bx 5%/APP 13%/nano-SiO2 2%. Mechanical properties of BPCs were analysed using flexural and tensile tests. While the flame and thermal properties of BPCs was improved significantly, the strength properties were marginally reduced due to application of FR additives. In general, APP as synergist with Ba-Bx improved thermal stability and flammability of BPCs.