Fabrication of Natural Filler Encapsulated Rigid Polyurethane Composite Foams Using Hemp-Seed Oil and its Enhanced Flame Retardancy

Abstract

Abstract Over the past few decades, polymer composites have been receiving significant interest and become a protagonist due to their enhanced properties and wide range of applications. Herein, we examined the impact of filler and flame-retardant in hemp seed oil-based rigid polyurethane foams (RPUFs) composite performance. Firstly, the hemp-seed oil (HSO) was converted to a corresponding epoxy analog, followed by a ring-opening reaction to synthesize hemp bio-polyols. The hemp polyol was then reacted with diisocyanate in the presence of commercial polyols and other foaming components to produce RPUF in a single step. In addition, different fillers like microcrystalline cellulose, alkaline lignin, titanium dioxide, and melamine (as a flame-retardant) were used in different wt.% ratio to fabricate composite foam. The mechanical characteristics, thermal degradation behavior, cellular morphology, apparent density, flammability, and closed cell content of the generated composite foams were examined. Initial screening of different fillers reveals that microcrystalline cellulose significantly improves the mechanical strength up to 318 kPa. The effect of melamine as a flame-retardant in composite foam was also examined which shows the highest compression strength of 447 kPa. Significantly better anti-flaming qualities than neat foam based on HSO have been reflected using 22.15 wt.% of melamine with the lowest burning time of 4.1 sec and weight loss of 1.88 wt.%. All the composite foams showed about 90% of closed-cell content. The present work illustrates the assembly of filler-based polyurethane foam composite with anti-flaming properties from biobased feedstocks with high-performance applications.