high-density polyethylene composites with treated perlite: thermal and mechanical properties

This study explores the development of high-density polyethylene (hdpe) composites reinforced with stearic acid-treated expanded perlite (tep) to examine their thermal, mechanical, and processing properties. the composites were fabricated using a plastograph at 200°c, incorporating perlite concentrations from 5% to 20% by volume. the effects of stearic acid (sa) treatment and perlite content were analyzed through sem, melt flow index (mfi), tensile and impact testing, and thermal analysis (dsc, tga, and vicat softening temperature). sem analysis revealed that untreated perlite exhibited a highly porous structure, while hcl treatment induced fragmentation. at 5% sa, perlite particles were well dispersed with a thin coating, whereas at 10% sa, the coating was more pronounced, leading to agglomeration. the mfi increased with perlite loading, reaching 12.3 g/10 min at 20% perlite, compared to 8.88 g/10 min for neat hdpe. mechanical testing showed that the elastic modulus increased by 36% (786 mpa) at 5% perlite, dropped to 460.8 mpa at 15%, and rose again to 707.7 mpa at 20%, suggesting structural reinforcement. moderate perlite content (5-10%) preserved ductility, while higher concentrations (15-20%), especially with 10% sa, increased brittleness due to reduced interfacial adhesion. thermal analysis showed a slight decrease in melting temperature and a slight increase in crystallization temperature with the addition of treated perlite, while thermal stability improved and the vicat softening temperature remained unchanged. these results highlight the potential of sa-treated expanded perlite as a viable alternative to conventional fillers, offering a balance between stiffness, ductility, and thermal resistance. the developed composites are promising for light weight and cost-effective applications in energy management and construction.