Manufacture and properties of ultra-low-density fiberboard

Low-density fiberboards with densities ranging from 0.05 to 0.50 g/cm(3) we re manufactured with steam injection pressing. Bond-type and foam-type isoc yanate compound resin adhesives were used separately at 10% and 30% resin c ontent levels. Two types of different-size fibers from softwood were used. Mechanical, dimensional, thermal, and sound insulation properties of the fi berboards were tested. The results are as follows: (1) Bond-type isocyanate adhesive showed higher mechanical and dimensional properties of low-densit y fiberboards than the foam-type adhesive. (2) Fiberboards produced from sm all fibers have better mechanical and dimensional properties than those mad e from large fibers. (3) Thermal conductivity of fiberboards depends more o n the board density than on the type of resin or fiber dimension, At a boar d density lower than 0.2g/cm(3), the thermal conductivity is almost equival ent to those of thermal insulation materials such as polystyrene foam and r ock wool. (3) Generally, the sound absorption coefficient of low-density fi berboards tends to increase at higher sound frequency. As the board thickne ss increases, low-frequency sounds are more readily absorbed by boards.