Development and characterization of thermal insulation materials based on rice straw and natural binder

Abstract

Thermal insulation is an essential factor to reduce energy demand during the stage of building operation. Nowadays, thermal insulation materials are however commonly produced from petrochemicals, causing high energy consumption and detrimental environment impact during production and arising the reuse and recycle issues. Insulation materials derived from local agricultural straws are becoming more attractive due to their availability, cost effectiveness, sustainability and low carbon footprint. Rice straw has the advantage of low density and low thermal conductivity due to its hollow internal structure. Also, the utilization of rice straw in buildings prevents the negative environmental impact of burning straw or mixing them with soil. The aim of this study is to develop an innovative composite insulation material from rice straw. A biobased binder, i.e., sodium alginate, derived from brown algae is used as binder. A modified method is developed to solve the water solubility issue of the composite material. The final product is rigid, lightweight and fully eco-friendly. The effect of fiber size and binder ratio (i.e., 8%, 16% and 24%) on the density, thermal conductivity and water vapor permeability are studied. The composite materials are insulating with thermal conductivity values in the range of 0.039-0.045 W/(m·K) for an average density in the range of 100 to 200 kg/m3.