Use of papermaking pulps in foam-formed thermal insulation materials

Foam-assisted forming technique was used to manufacture new types of highly porous materials (porosity 94-99%) using common papermaking pulps.The potential of these semi-rigid fibre panels as thermal insulation material was assessed. Foam forming utilises small air bubbles containing aqueous foam as a process fluid. Thick fibre panels from 100% softwood and hardwood cellulose and thermomechanical wood pulp were made in laboratory scale and the material properties were compared with selected commercial insulation products. The thermal conductivity of the materials was influenced only somewhat by the fibre raw material but the pulp selection had a large impact on airflow resistance and mechanical properties of the materials. Addition of cellulose microfibrils increased the strength of the materials but had a negligible effect on airflow resistance. The foam-formed fibre panels showed potential for positioning as the best wood fibre-based insulation material on the current insulation material markets with thermal conductivity that is competitive with mineral wools. Initial suitable applications for these new materials could be wall or ceiling insulation. By applying foam forming technique as a manufacturing process, wood originating from sustainable forestry practises may offer bio-based, easily recyclable and price-competitive raw material for the growing sector of insulation.