Abstract
Macro-voids in the core of uncompressed particle mats and pressed particleboard manufactured from novel particleboard furnishes were characterized using a response surface method with mixture design and X-ray CT technology. Industrial particles were screened into core-fine, medium, and coarse size classes and their dimensions were measured. Wooden blocks measuring 10 times the mean dimensions of these particles were cut and used as surrogates for the industrial particles. Novel particle mixtures were prepared by mixing together various proportions from each particle size class. The mixtures were packed to simulate particleboard mat formation and a pre-pressed particle mat. Panels were then fabricated from the industrial furnish mixtures. The void fraction of the packed particles and the finished panels were measured and correlated with the IB strength and edge screw withdrawal resistance. Results indicated that densely packed hammer-milled industrial particles had a maximum void fraction of 63.2%. The void fraction of a randomly packed, dense particle mat was described using a full cubic model. In both particle mats without resin and the pressed panels, increasing the core-fine content decreased void volume, whereas increasing coarse particle fraction increased void volume in the mat only. The macro-void ratio in the pressed panels increased exponentially with void fraction for the randomly packed, loose particle mats. Particle mixtures that resulted in boards with the smallest void fraction were not necessarily the strongest boards; low density particleboard panels made from the novel 100% coarse mixture were found to have the highest mechanical properties.
©2010 by Walter de Gruyter Berlin New York
