Characterization of Polyurethane Foam Reinforced with Seashell Waste Composites: Effects of Filler Type, Loading, and Particle Size

Abstract

Seashell waste bio-filler in polymeric material composites sustainably improves insulating performance. This study focuses on polyurethane foam composites (PUFc) reinforced with seashell waste powders and the effects of shell type, particle size, and filler loading on physical and mechanical properties and thermal conduction. Oyster, green mussel, and cockle shells were processed into 20, 40, and 80 mesh sizes and integrated into PUF at 10 to 30 wt% using the closed-mold method. Material characterization results shown by X-ray fluorescence analysis revealed calcium carbonate contents of 91 to 96 wt% in all shells. PUF with 20 wt% fillers, at 40 mesh, increased density, hardness, tensile strength, and compressive strength compared with neat PUF. The optimal formulation, oyster shell density (191 kg/m³), and cockle shell achieved a hardness of 86.7 Shore A. Tensile and compressive strengths were 1580 and 1352 kPa, respectively. Thermal conductivity slightly increased with filler additions. The optimal formulation of 20 wt% at 40 mesh oyster shell was 0.0472 mW/mK. However, water absorption increased with increasing filler content and particle size. Scanning electron microscopy-energy dispersive X-ray microstructural observations indicated improved filler dispersion and preserved closed-cell morphology at 20 wt%, 40-mesh filler loadings, values supporting the suitability of seashell-reinforced PUF as a sustainable building insulation material.