INFLUENCE OF JUVENILE WOOD ON DIMENSIONAL STABILITY AND TENSILE PROPERTIES OF FLAKEBOARD

The purpose of this study was to determine if juvenile wood adversely affects the linear expansion, water adsorption, and thickness swell of aligned flakeboard. Literature on juvenile wood properties and their effects on product performance was reviewed. Veneer and lumber cut fro m 35-year-old plantation-grown loblolly pine were segregated by age an d used to manufacture plywood and flakeboard. As expected, longitudina l linear expansion of the juvenile (0 to 12 years old) veneer was grea ter than that of mature (13+ years old) veneer. At several levels of h umidity exposure, linear expansion of symmetrical cross-laminated plyw ood made from the juvenile veneer was greater than that of plywood mad e from mature veneer. Significant increases in the linear expansion of three-layer cross-oriented flakeboard were also attributed to juvenil e wood. Differences in the linear expansion of single-layer directiona l aligned flakeboards made from juvenile wood and from mature wood wer e not statistically significant for the most part. Analysis did show t hat test results were affected by tree-to-tree variation in wood age a nd sample variations. Accurate predictions of dimensional stability in three-layer cross-aligned panels were made using tensile and linear e xpansion properties derived from the directional flakeboard.