Sustainable heat insulation composites from date palm fibre reinforced poly(β-hydroxybutyrate)

The use of natural fibre–reinforced bio-composites has been increasing over the past decade in construction and building applications. This study investigated the thermal insulation capabilities of date palm fibre (DPF)–reinforced poly (β-hydroxybutyrate) (PHB) composites fabricated via melt blending, compression moulding and annealing. The effects of DPF loading (10 wt%-50 wt%) on the fabricated composites were investigated to evaluate the physical, thermal and mechanical properties. Additionally, the obtained results of the developed composites were investigated and confirmed by SEM, DSC, FT-IR, TGA and bomb calorimeter. The result showed that the thermal conductivity of composites increased with DPF content and varied between 0.086 and 0.112 W/(mΔK) for various loadings of DPF. The heat capacity and thermal diffusivity of the composite were 1760 J/(kg.K) and 0.0474 mm²/sat maximum fibre concentrations (50 wt%), respectively. Furthermore, DPF addition to the PHB matrix increased the thermal stability of the composites. The composites containing 30 wt% DPF showed the maximum compressive strength (65 MPa) and exhibited thermal conductivity and thermal diffusivity of 0.092 W/(mΔK) and 0.041 mm²/s, respectively. However, the hollow structure of DPF declined the tensile properties of the composite. Addition of DPF reduced the gross calorific potential of the composites to 20.2 MJ/kg, which is lower than commonly used insulating materials. The water absorption was observed to increase with DPF contents, however it showed lower absorption values (3%) compared to the conventional thermal insulation material. Therefore, these findings show that this fully bio-based material composite can be a viable alternative for construction-related applications.