Sustainable rubber-modified HDPE composites reinforced with polystyrene and vermiculite for improved mechanical properties

Polymers are widely used in the aeronautical and automotive industries for their low weight and cost efficiency, but their structural use is often limited by insufficient stiffness, damping, or thermal stability. Among them, high-density polyethylene (HDPE) is valued for its toughness and durability, yet it still exhibits poor damping capacity and relatively low thermal resistance. To overcome these shortcomings, this work provides a comprehensive study on the design and characterisation of rubber-modified HDPE reinforced with polystyrene (PS) and vermiculite (VRM). The main objective is to combine the toughness of rubber-modified HDPE, the energy absorption of PS, and the thermal stability of VRM to develop hybrid composites with enhanced damping behaviour. The composites were manufactured by hot compaction (temperature: 180 °C, pressure: 30 MPa, and time: 20 min) of a rubber-modified HDPE matrix with variable ratios (5, 10, and 15 wt.%) of individual reinforcements by PS and vermiculite, which were ground prior to processing. A Scanning electron microscopy (SEM) was used to explore the improved interfacial bonding through diffusion between the matrix and reinforcements. Finite element (FE) analysis with a damage plasticity model reproduced the compressive behaviour, confirming the balanced stiffness – ductility of the PS-filled composites and the higher stiffness with reduced strain of the VRM-filled composites. These results demonstrated the development of advanced multifunctional composites through hybridisation of the rubber-modified HDPE matrix with PS or VRM and their potential to enhance the damping performance in demanding applications such as the aerospace and automotive industries.