This study had three objectives: (i) to determine the variation in moisture content (MC), basic density (BD), wood specific gravity (SPG), green density (GD), air-dry density (ADD), oven-dry density (ODD), radial shrinkage
, tangential shrinkage, volumetric shrinkage and the tangential to radial shrinkage
(T/R) ratio in G.
It also reduces radial shrinkage
, enabling cycle-time reductions in extrusion blow molding and injection molding of some parts.
Significant differences in BD and radial shrinkage
were also observed in the five trees of terap and of medang.
The molar ratios between the precursors (MR/FA, MR/Cat, W/MR or H/FA, H/Cat, methanol/H) were optimized, taking into account the final density, the preparation time and the radial shrinkage
Before and after the drying, the bulk gels were measured and their radial shrinkage
and density were calculated.
Percent radial shrinkage
(given in negative values) was calculated for 10 min time steps by relating the total radial shrinkage
(digital gauge, accuracy 1 [micro]m) to the total coupling pressure decrease.
The extreme case is a board cut just to one side of the center of the tree, so that one side of the board has only radial shrinkage
, and the other has considerable tangential shrinkage.
The coupling pressure decrease during dehydration induced by shrinkage (about 3 N in total) was related to the total radial shrinkage
(digital gauge, accuracy 1 um).
min]) = coefficient of radial shrinkage
of wood, and
This can be further explained by the significantly increased shrinkages (tangential shrinkage for the loaded LR specimen and radial shrinkage
for the loaded LT specimen) in the loading direction (Figs.
The mean radial shrinkage
from green to ovendry moisture content was 3.
The above characteristics of tangential shrinkage stresses are clearly different from the radial shrinkage
stresses, which tend to decrease with increasing RHs (Cheng et al.