Production of plastic-like moldings from fast growing tree's barks

点击翻译按钮获取中文摘要

Wiley-milled Acacia mangium outer bark samples were fractionated using a series of sieves according to their bark particle size. The extractive yields were affected by bark powder particle sizes regardless of the solvent ratio and extracting time, and at fractions under 45[], more than 50% methanol extractive yields were obtained. The average adjusted Stiasny value for the extractives was 94.5%, indicating that the tannin rich and is concentrated in the the small particle fractions. The gelation time of the mixture of methanol extractive formalin and water fenwith increasing pH from 4 to 8. Plywood was produced using lauan (Shorea spp.) rotary lathe veneers and adhesives prepared from bark powder with a particle size of lee than 63 [], paraformaldehyde and water. A shear strength of 11.7.kgf/cm2 after 72 hrs immersion in boiling, which complies with the requirement of the JIS K6802 for exterior-grade plywood, was attained. When the bark powder was added to a phenolic resin with 20% by weight of solid content of resin, the hot pressing temperature to obtain exterior-grade plywood could be reduced. Moulding products using a mixture of the bark powder and pulp in the ratio of 7:3 attained a bending strength of 80 MPa. After cold water immersion for 24 hrs, the bending strenght reduced to 70MPa.