Production and characterisation of wood-fibre insulation boards (WFIB) from hardwood fibres and fibre blends

Abstract

ABSTRACT Due to the rapid decline in coniferous (softwood) stands in Europe, the wood-based panel industry will be forced to adapt its products to the wood market supply. The production of wood fibre insulation boards (WFIB), which are usually made with softwood fibres, must therefore be converted to the use of hardwood fibres. The objective of this study was to investigate the properties of WFIB made from hardwood fibres and blends of softwood and hardwood fibres produced in a refiner by thermo-mechanical pulping (TMP). WFIB with a raw density of 100 kg m−3 were produced in a dry process with hot-air and hot-steam. The binder used was polymeric diphenylmethane diisocyanate (pMDI, 5 wt% related to the weight of dry fibre material) for stiff boards or 7 wt% bi-component (Bico) fibres for flexible mats. Mechanical strength results for pure hardwood fibres were significantly lower than for softwood fibres and for fibre blends, while water absorption was significantly higher. However, the thermal conductivity for pure hardwood fibres was higher than for softwood fibres and for fibre blends. The results showed that it is possible to produce WFIB from hardwood fibres with satisfactory properties. WFIB made from hardwood fibre blends with at least 20% softwood fibre content showed comparable results to those made from pure softwood fibres.