Production and evaluation of recycled LDPE composites with Hura crepitans seed shell reinforcement

Low-density polyethylene waste (LDPEw) recycling and improving its qualities with sustainable reinforcements have gained attention due to growing environmental worries about plastic buildup. The manufacturing and characterisation of recycled LDPE composites reinforced with lignocellulosic agricultural by-product Hura crepitans seed shell (HCSS) as an environmentally friendly filler are examined in this work. Using two-roll milling, recycled LDPE from used water sachets was combined with 0-30 weight percent (wt.%) HCSS before being compression-molded. Tensile, flexural, compressive, hardness, and impact strength tests were used to assess mechanical performance. Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis, and scanning electron microscopy were used to investigate structural and thermal properties, and quadratic regression modeling was used to determine the relationships between filler content and composite properties. Mechanical properties improved significantly at intermediate filler loadings, with peak tensile strength at approximately 10-15 wt.% HCSS and maximum impact strength near 24-25 wt.%. Hardness increased progressively with filler content, indicating enhanced stiffness. Thermal analysis confirmed the presence of stable lignocellulosic constituents and improved thermal resistance. Micro-structural observations revealed good dispersion and interfacial bonding at low filler contents, whereas higher loadings produced agglomeration and performance deterioration. Regression modelling validated nonlinear property responses and identified optimal reinforcement ranges. This work provides the first systematic regression-based optimization of recycled LDPE reinforced with Hura crepitans seed shell across a broad filler loading range. HCSS is therefore a viable reinforcement for developing value-added, sustainable polyethylene composites.