Dissertations in Forestry and Natural Sciences

Results
Table 6. The mechanical properties of the WPCs in studies III and IV (mean ±
standard deviation). The underlined values indicate at least significant (p 0.05)
difference in comparison with the other WPCs in the same study.
Property LG LG + HWD1 LG + HWD2 LG + HWD4 LG + HWD8
TS (MPa) 22.41 ± 0.82 22.85 ± 0.31 22.26 ± 0.30 22.05 ± 0.44 19.67 ± 0.52 **
TM (GPa) 2.09 ± 0.20 2.33 ± 0.09 ** 2.24 ± 0.06 2.16 ± 0.06 1.86 ± 0.11 **
(mm) 1.86 ± 0.26 1.81 ± 0.12 1.83 ± 0.15 1.92 ± 0.17 1.85 ± 0.13
FS (MPa) 44.09 ± 2.00 45.27 ± 1.01 43.09 ± 0.83 42.86 ± 1.17 39.36 ± 0.63 **
MOE (GPa) 3.05 ± 0.16 3.21 ± 0.08 3.11 ± 0.12 2.89 ± 0.09 * 2.73 ± 0.09 **
B (mm) 4.54 ± 0.28 4.42 ± 0.28 4.37 ± 0.30 4.72 ± 0.29 4.67 ± 0.27
CIS (kJ/m 2 ) 11.57 ± 2.02 10.61 ± 1.27 11.17 ± 0.81 10.89 ± 1.13 9.42 ± 0.69 *
Property LG + SWD1 LG + SWD2 LG + SWD4 LG + SWD8 LG + SWD20
TS (MPa) 21.13 ± 1.03 * 23.54 ± 0.66 ** 22.45 ± 0.81 19.51 ± 0.79 ** 15.46 ± 1.56 **
TM (GPa) 1.98 ± 0.18 2.16 ± 0.06 1.96 ± 0.10 1.60 ± 0.10 ** 1.07 ± 0.23 **
(mm) 1.94 ± 0.12 2.07 ± 0.15 2.13 ± 0.12 * 2.18 ± 0.14 ** 2.60 ± 0.39 **
FS (MPa) 43.04 ± 2.48 45.47 ± 1.40 40.81 ± 4.08 39.39 ± 1.41 ** 32.80 ± 2.38 **
MOE (GPa) 2.91 ± 0.28 3.10 ± 0.07 2.58 ± 0.33 ** 2.34 ± 0.15 ** 1.70 ± 0.29 **
B (mm) 4.71 ± 0.21 4.73 ± 0.27 5.21 ± 0.35 ** 5.59 ± 0.30 ** 6.65 ± 0.71 **
CIS (kJ/m 2 ) 10.40 ± 1.52 12.08 ± 2.12 12.22 ± 1.65 11.26 ± 1.41 10.63 ± 1.14
* p 0.05 (a significant difference compared with the unmodified WPC).
** p < 0.01 (a highly significant difference compared with the unmodified WPC).
LG = LunaGrain, HWD = Hardwood distillate, SWD = Softwood distillate,
TS = tensile strength, TM = tensile modulus, = strain, FS = flexural strength,
MOE = modulus of elasticity, B = bending, CIS = Charpy’s impact strength.
7.2 WATER ABSORPTION
Water absorption of WPCs was determined in studies I, III, and
IV. In study I, the addition of hardwood distillate did not have
any consistent effects on the amount of water absorbed by the
UFs; for example, when distillate-treated LG was added to UF20,
a minor increase was observed in water absorption, but the
opposite effect was detected for UF30 and UF50. However,
when 4.2 wt% of distillate was added to LG, water absorption
reduced by over 30%.
In study III, the addition of hardwood distillate considerably
decreased water absorption of the WPCs (Figure 14). The major
differences occurred during the first 24 hours of immersion as
the differences between the material types remained more or
Dissertations in Forestry and Natural Sciences No 222 89