PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 6, Number 2, 2020
to filtration (SRF) and capillary suction time (CST) as indicators and the Box – Behnken design of response surface methodology (RSM). Results indicated that the moisture content of cake, SRF and CST decreased from 74.52 to 69.57%, 25.39 × 1012 to 11.80 × 1012 m/kg and 199.8 to 146.4 s, respectively, under optimal conditions. RSM results presented that only 0.13% of the response values cannot be interpreted with this model, and the three Ǧ factor interaction was observed to be significant. Additionally, sludge dewaterability mechanism observed that K2S2O8 mixed with paper sludge used the strong oxidising properties of SO4−• to crack sludge flocs. Fine fibres and calcium carbonate in the paper sludge played important roles as the skeleton support in the sludge filtration process, and the internal moisture was rapidly eliminated. WOOD PANEL Tuning of adhesion and disintegration of oxidized starch adhesives for the recycling of medium density fiberboard, Lubis, M.A.R., Park, B., and Hong, M., BioResources , 15(3), DOI: 10.15376/biores.15.3.5156-5178. Oxidized starch (OS) adhesives with a balance between their adhesion and disintegration properties were prepared by controlling the degree of oxidation and modifying the cross-linker type and level to replace urea- formaldehyde (UF) resins for easy recycling of medium density fiberboard (MDF). Four molar ratios of H2O2/starch, two types of cross-linker, i.e., blocked-pMDI (B-pMDI) and citric acid (CA), and three levels of the cross-linkers were employed to tailor the performance of the OS adhesives. The OS reacted with the isocyanate groups from the B- pMDI to form amide linkages, while it formed ester linkages by reacting with the CA. The resulting B-pMDI/OS-bonded MDF had better physical and mechanical properties than the CA/OS-bonded MDF, with comparable adhesion (0.34 MPa) to UF resins and ten times greater degree of fiber disintegration than UF resins. The combination of a 0.5 molar ratio OS with 7.5 wt% of B-pMDI produced MDF exhibiting an optimal balance between adhesion and disintegration, suggesting that such OS adhesives could someday replace UF resins in manufacturing and recycling of MDF without formaldehyde emission. Properties evaluation by thickness and type of oriented strand boards manufactured in continuous press line, Zeleniuc, O., Dumitrascu, A.-E., and Ciobanu, V.D., BioResources , 15(3), DOI: 10.15376/biores.15.3.5829-5842. Oriented strand boards (OSB) are widely used in construction replacing plywood. There are four types of boards (OSB/1, OSB/2, OSB/3, OSB/4) carried out depending on the conditions of uses. The present research aimed to evaluate the physical and mechanical performance of these types of boards, with 10 mm, 11 mm, 18 mm and 22 mm thicknesses. The boards were industrially manufactured using the continue press line. The results showed that the compression grade increased with decreasing of the wood strands densities, from 1.3 (OSB/1) to 1.1 (OSB/3). Thickness swelling values were lower for OSB/3 and OSB/2 with 35% and 14%, when compared to OSB/1. For these boards a slight increase in adhesive content and a lower speed of pressing line was set considering that they are designated for the exterior use. An increase in density with about 7.6% led to an increase with about 19% of modulus of rupture (MOR), when compare OSB 10 mm with OSB 22 mm. Improvements with 27% to 22% MOR and 13% to 10% modulus of elasticity (MOE) in case of OSB/3 and OSB/2 compared to OSB/1 were found. Internal bond (IB) values were with about 32% higher for OSB/3 than those reached by OSB/1 and the thinner boards registered 25% higher IB values even after boiling test, compared to the thicker ones.
Technical Abstracts
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