Sustainable UPE Composites Reinforced with Recycled HDPE: Correlation of Mechanical, Thermal, and Acoustic Performance

Abstract

This paper produces environmentally friendly unsaturated polyester resin (UPE) composites that use finely ground high-density polyethylene (HDPE) particles (approximately 53 μm, 0-10 wt.%). Mechanical, thermal and acoustic properties were assessed systematically in order to identify structure property relationships. Incorporation of HDPE enhanced compressive strength (56.6→94.4 MPa), impact resistance (+70%), surface hardness (75.4→80.5 Shore D), thermal conductivity (0.19→0.26 W/m².°C), and sound insulation (≈ 20 dB reduction at 10 kHz). On the other hand, flexural strength declined (>80%). FTIR was used to confirm the chemical stability of the recycled HDPE following remelting, whereas microscopy was used to identify homogeneous dispersion of the reinforcing particles as the cause of enhanced damping and toughness. The results indicate the possibility of using recycled HDPE as a versatile filler that could allow creating lightweight, low cost, and environmentally-friendly UPE composites used in acoustical and energy-absorbing applications.