Abstract
In this study, the physical and mechanical properties of cell wall of newly formed compression wood of Japanese black pine (Pinus Thubergii Parl.) have been investigated.
The results obtained are summarized as follows:
(1) When the compression wood was formed in a tree, a large compressive stress resulting from growth stress appeared at the tissue near cambium. Its compressive stress level was about 10% of the tensile strength.
(2) The tensile strength of the compression wood was smaller than that of normal wood or cell wall near cambium.
(3) The relaxation quantity (σt/σ0) of compression wood was larger than that of normal wood.
(4) The relaxation quantity in the compression wood decreased as the lignification of cell wall progressed.
(5) The restrained dry wood under tensile stress (about 20% of tensile strength) showed a different cell wall condition of tracheid than the unrestrained dry wood. The most pronounced difference appeared in their shapes of pits on the radial section.
