Investigation of physical, mechanical and thermal properties of hemp and camelina reinforced polymer composites

The use of agricultural wastes in composite materials contributes to waste reduction and encourages the use of renewable resources. This study aims to develop sustainable building materials by utilising agricultural wastes (hemp and camelina) and perlite in the production of building materials. The study aims to offer solutions to the building sector in the field of thermal insulation, lightness and environmentally friendly materials, thus providing both environmental and technical advantages. A flame-retardant polyester (FRP) matrix was used as the base material (20 % by volume), while the reinforcement content consisted of 80 % agricultural fibers. Hemp and camelina were combined with 0 %, 10 %, and 20 % perlite to produce various composite groups. Camelina content was systematically adjusted, replacing hemp at 20 % of the reinforcement. Key findings revealed that increasing camelina content resulted in reductions in apparent density, water absorption, porosity, compressive strength, and thermal conductivity. Conversely, perlite addition enhanced the apparent density, ultrasonic pulse velocity (UPV), and compressive strength of the composites. The lowest thermal conductivity value was obtained as 0.0964 W/(m.K). Furthermore, the composites' fire performance was evaluated through reaction-to-fire behavior and limiting oxygen index (LOI) tests, while thermal degradation was analysed via thermogravimetric analysis (TGA). The microstructural features of the composites were examined using scanning electron microscopy (SEM), providing insights into the interactions between matrix and reinforcement phases. The study demonstrate that tailored reinforcement ratios significantly influence the mechanical and thermal properties.