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MATERIALS 55
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influenced the overall orientation of the strands, with the absorption (WA) and thickness swell (TS) of the specimens.
strands in the lower part of the panel having a more random Again, five specimens of each panel type were tested, and
distribution. the results were calculated after 2 h and 24 h of complete
The orientation had a profound influence on the mechanical immersion in water. Five points on each specimen were

properties of the panels, especially tensile properties. Thus, pre-marked to measure the thickness swell, before and after
the study aims to provide a comparison of all the properties, water soaking.
where the forming technique was constant for fabricating both Deionised water was again utilised, and the total moisture
panel types, with virgin and re-resinated strands. uptake after 24 h was calculated according to ASTM D4442-20
The influence of reprocessing the re-resinated strands was standard, after oven drying for 24 h at 105 deg C. All the WA,
evaluated by testing specimens from hot-pressed panels for TS, and moisture uptake results were plotted in percentage
their dimensional stability, mechanical performance, and fire increase from the conditioned samples.
performance.
All the tests were carried out as per ASTM standard Mechanical Performance

specifications. Specimens were conditioned for about three Vertical density profiles (VDP) of both panel types were
to four weeks before testing at 20 deg C and 65 percent analysed using an X-ray vertical density profiling machine at
RH to achieve an equilibrium moisture content of 12 percent. CMEC, WSU. Specimens measuring 50.8 mm by 50.8 mm
were tested to examine density variations along the panel
Dimensional Stability And Moisture Interaction thickness. 10 specimens from each panel type were evaluated.
Dimensional stability is crucial for wood and wood-composite Studies have demonstrated that resin content plays a
panels due to wood’s inherent hydrophilic nature. This limits significant role in determining the mechanical performance

the applications of wood-based materials, particularly in high- of wood-composite panels.
moisture environments. Therefore, following non-destructive testing for panel
Understanding the interaction between panel surfaces density through thickness, the same specimens were subjected
and water is essential for determining panel wettability and to internal bond (IB) strength analysis according to ASTM
overall performance. D1037-13 standards.
Research has shown that resin content directly influences With a testing speed of 0.508 mm/min, based on the 6.35
the hydrophilic nature of the final panel, with higher resin mm panel thickness, IB strength was assessed as a critical
content resulting in increased hydrophobicity. parameter for ensuring proper curing and bonding of pMDI
To assess surface wettability, the surface contact angle and

surface tension using the sessile drop method was calculated, Pixabay
following the ASTM D7490-13 standard.
The process involved using a VCA Optima video system.
Employing a Hamilton 81020 syringe (100 µL capacity), deionised
water was dispersed uniformly on the specimen surface.
Five specimens for each panel type were tested. Eventually,
to understand the performance of the entire panel when

exposed to a high moisture environment, Method A of ASTM
D1037-13 standard was employed to estimate the water