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MATERIALS 53
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The dimensional distribution of the furnish particles showed Distance bars were used during hot-pressing for consistent
that LS-/ contained 19.4 percent particles <0.5 mm, 20.7 board thickness.
percent particles 0.5–1 mm, 43.5 percent particles 1–2 mm,
and 16.2 percent particles >2 mm. LS-I contained 35.3 percent Evaluation
particles <0.5 mm, 17.6 percent particles 0.5–1 mm, 14.6 The obtained particleboards were characterised according
percent particles 1–2 mm, and 32.4 percent particles >2 mm. to relevant standards by determining the density, modulus

RE contained 12.8 percent particles <0.5 mm, 27.6 percent of elasticity (MOE) and modulus of rupture (MOR) in a three-
particles 0.5–1 mm, 26.2 percent particles 1–2 mm, and 33.4 point bending test, tensile strength perpendicular to the board
percent particles >2 mm. surface (IB), thickness swelling (TS) and water absorption
Ethanol-extracted birch outer bark was ground to pass a (WA) after 24 hours immersion in water, and face withdrawal
2 mm sieve and hydrolytically depolymerised in a 4 percent of screw resistance (WSR).
KOH solution for 30 minutes. In addition, surface optical morphology was performed with
The filtered wet product with a moisture content of stereoscopic light microscopy equipped with image acquisition
approximately 75 percent was used as the SA-based binder software, analysing face and cross sections of the boards at
(solubility in tetrahydrofuran ~54 percent, monosaccharides 2× magnification.

11.4 percent, ω-hydroxy acids 17.1 percent, α,ω-diacids ~20.8 Five specimens were tested for each property to calculate
percent, triterpenes 11.0 percent, acid number ~49 mg KOH/g) the average value for each particleboard type.
without any additional additives. The resulting board properties were compared with the
Three-layer particleboards were produced using the three European requirements specified in EN 312 for particleboards
furnishes described above. To utilise all fractions of sawn LS intended for interior fitments (including furniture) for use in dry
particles, the face layers were formed from particles with a conditions (Type P2). The influence of selected factors on the
fraction <1 mm, while the core layer consisted of particles mean property values was analysed at a confidence level α =

>1 mm. 0.05 using one-way ANOVA and correlation tools.
Based on a previous study, 21–25 wt. percent (dry basis)
of wet SA binder was added to the LS furnishes, and 15–21 Properties Of Obtained Particleboards
wt. percent was added to the RE furnish. The obtained particleboards exhibited a brown coloration
The blended furnishes were then dried (MC < 2 percent) due to the SA binder and showed good machinability and
and hot-pressed at varying temperatures (190–220°C) and surface roughness.
pressing times (0.9–1.7 min/mm) to obtain particleboards with
final dimensions of 9 mm × 300 mm × 300 mm, with target
densities ranging from 650 to 850 kg/m³. www.freepik.com

The pressing cycle for all board types consisted of four
stages: pressing at maximum pressure (3 MPa) to reach the
target thickness for 3.5 minutes; releasing the pressure at
0.2 MPa for 30 seconds; pressing at reduced pressure (<2
MPa) to stabilise the thickness for three minutes; and pressing
under minimum pressure (0.5 MPa) until the end of the set
pressing time.