Thermal insulation performance of composite materials using industrial hemp straws

In response to the need for increased utilization of industrial hemp straws and to mitigate the environmental burden of biomass waste, this study investigates the development of an eco-friendly, lightweight building insulation material. The composite material was prepared by combining industrial hemp straws and cement as the primary matrix, with vitrified microbeads serving as insulating fillers and polyvinyl alcohol (PVA) to enhance overall toughness. Orthogonal tests, range analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were employed to evaluate the effects of varying proportions of industrial hemp straws, vitrified microbeads, and PVA fibers on the thermal insulation, compressive strength, water absorption, and dry density of the composite.Results reveal that the composite with the A 2 B 2 C 2 formulation achieved a thermal conductivity of 0.182571 W/(m·K), a compressive strength of 4.83 MPa, a water absorption rate of 0.34162%, and a dry density of 0.847 kg/m³. This formulation meets the MU3.5 grade for compressive strength (≥ 3.5 MPa), making it suitable for use in lightweight structural insulation components. In contrast, the A 3 B 4 C 4 formulation exhibited a lower thermal conductivity of 0.11684 W/(m·K), a compressive strength of 1.02 MPa, a water absorption rate of 0.80324%, and a dry density of 0.552 kg/m³, making it ideal for insulation layers in non-load-bearing walls where high thermal insulation is essential. The composite material based on industrial hemp straws shows considerable potential as an innovative building insulation solution for applications in cold climates.