Bio-based foam for thermal insulation. Valorisation of CNSL (cashew nut shell liquid)

Abstract

Everyone now knows that the building industry accounts for 43% of energy consumption and 25% of greenhouse gas emissions. It thus constitutes one of the key objectives in the pursuit of the "Factor 4" issues in 2050. The thermal insulation defects of buildings and mistreatment of airtightness problems are the main causes low energy performance of the built French park. The fight against energy waste therefore passes deals with the thermal insulation of heated buildings. The thermal insulation performances are firstly determined by their thermal conductivity and the physical quantity characterizing the behaviour of materials during the heat transfer by conduction. With an average thermal conductivity of 0.023 W/m.K, polyurethane foam remains very good for building insulation. The advantage of this material therefore results in a gain of living space. Indeed for a given heat resistance, the thickness of material required is lower than for the homologous. However, PU foams are generally expensive especially because of the presence of fossil compounds as well as adverse effects on the environment and health (discharge of volatile organic compounds VOCs). In 2007, the French chemical industry is committed to use by 2017, 15% of bio based raw materials and diversify its industrial resources used (agricultural resources, especially non-food processes, and lignocellulosic waste and coproducts). However, only 8% of raw materials of the French chemical industry are renewable. Polyurethane foams are generally composed of two main compounds: Polyols, and isocyanate, the both from fossils resources. There is today part of a solution dealing with bio polyols from rape seed oils, but in most of case too much expensive for this industry. CNSL (Cashew Nut Shell Liquid) is a co-product of cashew nut exploitation. It is a kind of vegetal oil mainly composed of anacardic Acid and cardanol. This oil may be a very performant and low coast raw material ($ 300/ton) for polyol production to substitute fossil polyols in Polyurethane composition. CoDEM is today developing new bio based expanded foam with CNSL to reach a target thermal conductivity near 0,025 W/m.K This communication may explains the first part of our works substituting polyols and first results measured in our laboratory.