Development of Sustainable Multilayer Composite Nonwoven Fibrous Assembly for Thermal Insulation Application

Insulation offers thermal comfort by blocking the heat flow across the walls of buildings and drastically reduces the cost associated with energy consumed in maintaining temperature inside the buildings. Commercial insulating materials such as fiberglass, polystyrene, and polyurethane foams, although demonstrating long serviceability, are associated with several limitations including non-biodegradability. This study hence presents the development of biodegradable multilayer nonwoven fabrics based on natural fibers for thermal insulation as a sustainable alternative to synthetic non-biodegradable polymers. The nonwoven fabrics of kapok, jute, and banana with thicknesses ranging between 5 and 15 mm were produced by needle punching. The developed needle punched nonwoven fabrics were attached together in different fiber combinations to produce multilayered fabrics. The nonwoven fabrics were investigated for thickness, areal density, porosity, and thermal properties like heat flux, thermal resistance, and thermal conductivity. The relatively low thermal conductivity of kapok, jute, and banana fibers, and presence of air pockets in the needle punched nonwoven fabrics, all together governed the development of a sustainable fibrous assembly for thermal insulation of buildings. The results confirmed that kapok, jute, and banana fiber based nonwoven fabrics can be successfully used as an alternative to conventional non-biodegradable thermal insulating materials.