Miscanthus and flax as raw material for reinforced particleboards

Single-layer particleboards from Miscanthus and a three-layered variant with poplar strands in the surface layer were produced and tested in the laboratory. It was found that standard particleboards can be produced from the raw material Miscanthus sinensis provided the glue used is PMDI, while the use of UF, PF and MUFF adhesives lead to boards with low mechanical strength properties. All three-layered boards were produced with 5.5-6% and 4.5-5.0% PMDI as adhesive in the surface and middle layers, respectively. In all variants the middle layers consisted of 50% beech and 50% Miscanthus chips. Compared with the mixed variants the pure Miscanthus boards showed surprisingly good results and conformed to DIN 68763 standard values. Tests were also carried out to find out whether it would be possible to produce particleboards with high bending strength by adding OSB poplar strands and Miscanthus strands to the surface layers. The strength properties of these boards were in the range of those for glass-fibre reinforced and flax fibre reinforced wood particleboards. Reinforcement with flax straw mats was effected with weight portions of 3 and 6% related to oven-dry chip mass. The mats were sprayed with glue and then placed in the surface layer. This led to a maximum increase in bending strength and E-modulus in bending of 60 and 40%, respectively. Pure Miscanthus particleboards can be effectively reinforced with flax fibres. The mechanical strength properties here exceeded those of conventional wood particleboards by about 50%. (C) 1998 Elsevier Science B.V. All rights reserved.