Page 44 - FDMAsia SepOct 2024

42 TECHNOLOGY SEP/OCT 2024 FDM ASIA | www.fdmasia.com

PickPik For IB, the size of the particles is crucial, especially in the
core layer. As observed during the milling of window frames,
wood particles tend to shorten compared to conventional
particles.

This is partly due to the presence of finishes, particularly
clear varnish, which penetrates the wood more deeply and
contributes to its increased brittleness. This brittleness leads to
a more pronounced reduction in particle size, not only during
milling but also during the process of gluing the particles.

Internal Bond Screw Withdrawal Resistance
The results of the internal bond test are depicted. Notably, Screw withdrawal resistance is shown. The lowest SWR values
most variants failed to meet the minimum IB requirements. were recorded for variants where the alternative crude was 5

The IB values are as follows: for particleboards made from (106 N mm−1), 10(86 N mm−1), and 25 (111 N mm−1) parts
white-painted window frames, the highest value was recorded by weight for particleboards made from white-painted window
for the variant made entirely from alternative particles, at frames. The highest value was recorded for the variant made
0.47 N mm−2, which is lower than the reference value of entirely from alternative particles—139 N mm−1.
0.61 N mm−2. For the particleboard made of particles with clear varnish,
Only this variant met the standard requirement for IB, the highest value was 165 N mm−1; the values obtained were
which is 0.35 N mm−2. For samples made from window even higher than for the reference board. The lowest SWR

frames coated with clear lacquer, the highest IB value was value for particleboards made from window frames with clear
also recorded for the variant made entirely from recycled varnish was recorded for the variant where recycled particles
particles, achieving 0.89 N mm−2, which was higher than accounted for 25 parts by weight—97 N mm−1.
the reference value. The density of the substance under test determines SWR,
Similarly to the boards with white paint, only this variant which can significantly increase as density increases. In
from the series of samples with clear lacquer met the standard contrast, other studies report that recycled wood contributes
requirements. to lower SWR values. Still, it is worth bearing in mind that the
The weakest IB performance in both cases was observed recycled raw material and, above all, its form does matter,
in samples where the alternative raw material constituted so it is essential to use more significant fractions, especially

10 parts by weight—0.09 N mm−2 (white paint) and 0.13 N in the core layer.
mm−2 (clear varnish).
Thermally modified wood (TMW) was tested for recycling Water Absorption & Thickness Swelling
into a three-layer particleboard. Boards were produced with Water absorption decreased as the post-treatment wood
recycled wood contents of 0, 20, 50, and 100. As the TMW content increased after two and 24 h. The particleboards
content increased, the IB value decreased. The thermo- made entirely of post-consumer wood and coated with clear
modification of wood mentioned above can adversely affect varnish exhibited the best dimensional stability.

the wettability and, thus, the sticking of wood particles, which After two h, for the variant with zero percent alternative raw
is confirmed by similar studies using TWM. material (varnish one), the water absorption was 87.4 percent;