Wood polymer composite (WPC) formulation from Ethiopian indigenous lowland bamboo particles and post-consumer plastic blends: synergetic and dual effects of both coupling agent and organic crosslinking catalyst

Currently, the rapid increase of potential thermoplastic waste, which does not circulate back into ecosystem through biodegradation, has led to valuable resource waste and environmental pollution. To utilize the economic value and reduce environmental impact, ecofriendly biomass-based wood polymer composites (WPCs) were produced from potential thermoplastic waste blends. Both recycled polystyrene (rPS) from electronic waste and recycled high-density polyethylene (rHDPE) from post-consumer waste were used as polymeric matrices. Ethiopian indigenous lowland bamboo particles (Oxytenanthera abyssinica), which had never been used in WPC, was utilized as the dispersed phase reinforcement. The formulation involves in situ reactive melt blending and chemical crosslinking using maleic anhydride grafted polypropylene (MAPP) and dicumyl peroxide (DCP) as an organic catalyst initiator, without preliminary solvent-based bamboo particles treatment. The properties of WPCs formulated from varying sizes of LLB particles and compositions of rHDPE, rPS, and their equal melt blends were thoroughly investigated using established standards. Similarly, the chemical composition, structure, crystallinity, thermal degradation, and contaminants of the recycled plastics, as well as the composition of indigenous LLB, were carefully evaluated and characterized before use. In situ melt blending and reaction induced crosslinking interfaced with MAPP compatibilizer and DCP crosslinking synergistically enhanced the composite properties, which were not achieved with separate polymer matrices. The result shows a very significant increase in fundamental static and dynamic mechanical properties, including thermal stability of the composites compared with uncoupled composites. Formulated WPCs can provide low-cost and sustainable building materials which can replace energy intensive and non-sustainable conventional building materials.

Graphic Abstract

Wood polymer composites (WPCs) were produced using blends of recycled polystyrene (rPS) and recycled high-density polyethylene (rHDPE) from post-consumer waste with Ethiopian indigenous lowland bamboo particles (Oxytenanthera abyssinica). The formulation involves in situ reactive melt blending and chemical crosslinking using maleic anhydride grafted polypropylene (MAPP) and dicumyl peroxide (DCP) as an organic catalyst initiator, without preliminary solvent-based bamboo particles treatment.