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

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-SiO 2) 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-SiO 2 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. The effects of boron compounds (BCs) utilization as synergists with ammonium polyphosphate (APP) on the mechanical and fire retardant (FR) properties of wood polymer composites (WPCs) manufactured from wood flour, HDPE, MAPE is known through work by Kurt et al. (2012). BCs acts as synergist with APP, however, reduced mechanical properties of WPCs is an imminent result in this combination. Studies in the past have reported on reduced strength properties of wood or lignocellulosic biomass due to BCs treatment (Nagieb et al., 2011; Toker et al., 2009 etc). Further, additives with nano-scale, such as nanoclay, carbon nanotube, and nano-SiO2 are incorporated to polyethylene, polypropylene, and acrylic polymer for improving the tensile and flexural properties of the composites. Thermal stability, hardness, flame retardancy, and water resistance capacity were also found to enhance with addition of nano SiO 2. Pan et al. (2014) have investigated the synergistic effects of the combination of APP and nano-SiO2 on the flame retardant properties of WPCs, and APP/nano-SiO2 has significant improvement on heat release rate, total heat release, time to ignition, mass loss rate, and limited oxygen index. The most efficiency was appeared in APP 8%/nano-SiO2 6%. There is little or no information on synergistic effects of the combination of BCs, APP and nano-SiO2 on the flame retardancy, strength, thermal and recyclability properties of WPC. [ABSTRACT FROM AUTHOR]