Combustion characteristics and mechanical properties of wood impregnated with a paraffinic phase change material

In this contribution, investigations towards multifunctional wood and timber elements impregnated with phase change materials (PCM) are presented. The purpose of the PCM impregnation is a passive air-conditioning by structural timber elements like beams, walls or ceilings and non-structural elements like flooring or wall panels. PCM have the ability to take up substantial thermal energy within a narrow, latent temperature range without increasing their temperature. The high specific heat capacity combined with low additional mass can improve the room climate in timber buildings, which have often, especially in the summer, unpleasant temperature amplitudes without active air-conditioning due to low thermal mass. In order to produce PCM-impregnated timber elements, several investigations are performed. As a first aspect, investigations related to the mechanical behaviour of PCM-impregnated wood are presented. The investigations show that in its solid state the PCM can improve the mechanical properties. In the liquid state of the PCM, the mechanical properties of the impregnated wood are on the level of PCM-free wood. A second aspect, which was investigated, is the combustion behaviour. Investigations with cone calorimetry showed that directly flamed PCM-impregnated wood acts as fire accelerant. However, reaction to fire tests of laminated non-structural elements also showed that a proper protection from direct contact to fire could enable a safe use of PCM-impregnated wood in construction elements.