PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 8, Number 2, 2022
yield of bio-oil of 41.9wt% was obtained at the temperature of 450°C. Gas chromatography (GC) was used to determine the chemical composition of the liquid oil product. The results shows that pyrolyzing MDF might produce renewable fuels by prevent the environmental issues associated with waste management. “Influences of hardening agent on some physical and mechanical properties of medium- density fibreboard”, Osman Ç amlibel & Murat Aydin, Turkish Journal of Forestry , Vol.23 (2), pp.128-134 (2022). Effects of Ammonium chloride (NH4CI) as a hardening agent on thickness swelling (TS), water absorption (WA), screw holding resistance (SHR), Janka hardness, modulus of rupture (MOR), modulus of elasticity (MOE), and internal bonding (IB) properties of medium-density fiberboard (MDF) were evaluated. Target densities were 712 and 715kg/m³ for hardener applied (0.75kg/m³ solid as 10% solution (fiber dry wt.)) and unmodified factory made 18mm thick MDF, respectively. A total of 400 samples were tested. Boards produced without hardener presented better mechanical properties except for SHR. Indeed, SHR was around 9.2% improved by hardener utilization. However, hardener utilization caused around 8.4%, 7.3%, 3.6%, and 1.3% decreases for MOE, MOR, IB, and Janka hardness, respectively. Surprisingly, soaking time caused opposite results for TS and WA. The TS and WA of the hardener utilized MDF decreased around 40.3% and 29.6% for short-term soaking (2h) but remarkable increases (around 62.4% and 20%, respectively) were observed for long-term (24h) soaking. Statistical analysis proved that there were statistically significant (P<0.05) differences between all the evaluated properties. “Effects of application conditions on the bending strength of oriented strand board (OSB)”, Chen Chaoyi, Li Wanzhao & Mei Changtong, Journal of Beijing Forrestry University , 44(6), pp.138-134 (2022). Objective Oriented strand board (OSB) is composed of cross-oriented layers consisting of thin and rectangular wooden flakes or strands, which are compressed and bonded together with synthetic resins. OSB is an important engineered wood product. The influence of application environment on the bending properties of OSB can provide necessary theoretical support for optimizing the processing technology and application method of OSB. Method Samples prepared from 13mm thick OSB panel were conditioned under different relative humidity (RH) conditions. Three-point bending tests were performed to measure the fatigue deflection of OSB under cyclic loading, strain distribution was recorded using digital image correlation (DIC) simultaneously. This contributes to reveal the causes of deflection results. Result: The increase of RH increased the moisture content and thickness of OSB, and enlarged the voids among wood strands and cracks in wood strands. The deflection of OSB increased significantly after conditioning at (95 ± 3)% RH, and after conditioning the samples at (65 ± 3)% RH, the deflection was still larger than the initial deflection. The samples’ deflection was close to their initial deflection if conditioning them at (95 ± 3)% RH and (65 ± 3)% RH without adding loading. The effect of loading cycles on the deflection was slight when the samples were conditioned at unchanged (65 ± 3)% RH. The deflection of the first cycle loading obviously increased, which was not found as increasing loading cycles. Strain distribution was homogeneous if the samples were conditioned only at (65 ± 3)% RH. The increase of moisture content could hamper the strain transfer and induce strain accumulation. Specifically, bending strain was prone to accumulate on the top and bottom surfaces, and shear strain would occur in the two opposite directions in high moisture content samples. Conclusion: The findings of this work explore the effect of application conditions and loading cycles on the bending strength of OSB. The outputs of this work are helpful for optimizing the manufacturing strategies and enlarging application field of OSB.
Technical Abstracts
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