Iranian Journal of Wood and Paper Science Research
Year:2020 | Volume:35 | Issue:3 (72)|Papers Count:7

This study was carried out to investigate the effect of bagasse alkaline treatment usig hydroxide sodium on medium density fiberboard (MDF) properties made from bagasse. For this purpose, Depithed bagasse from wet storage was used. Heat treatment was done in 10 liters digester with liquor to bagasse ratio of 10 to 1. Sodium hydroxide dosage was selected at 0%, 4% and 5% based on oven dry weight of bagasse. Cooking time and temperature were 5 min and 170 ° C, respectively. Fiber morphology of prepared bagasse wqas determined using an optical microscope. Chemical components including holocelloulose and lignin contents were also determined. Liquor pH was mesearued before and after cooking. Urea formaldehyde (UF) resin was used as binder for MDF production. UF Resin content was 12% based on oven dried weigth of bagasse. Bending properties (MOR & MOE), internal bonding and thickness swelling of the boards were determined based on EN-310, EN-319 and EN-317 standards, respectively. The results showed that the minimum fibers cutting and crushing were obtained using 4% alkaline treatments. Lignin content decreased by increasing of sodium hydroxide content, but holocelloulose content increased. Also increasing of sodium hydroxide dosage resulted in increasing the bulk density. The maximum MOR, MOE and internal bonding of the boards were obtained at 4% sodium hydroxide dosage. Thickness swelling after 2 and 24 hours immersion of the boards was minimal at 4% sodium hydroxide dosage.

The aim of this study was to investigate the performance of mitered corner joints (L-shaped) reinforced by fibers reinforced polymer (FRP) at maximum stress area under diagonal compression loading. In this way, the performance of fabricated corner joints of two wood species (beech and fir) reinforced by fiber reinforced compopste using epoxy as matrix and one and two layer of carbon and glass fibers as reinforcement were determined. After fabrication of the mitered joints with using dowel and polyvinyl acetate adhesive, the joints were reinforced with FRP composites and then were subjected to diagonal compression loading. Results have indicated that reinforcing layers prevent joint opening. However, failure was occurred at the joint by peeling fibers from wood surface or members fracture near the joints due to stress concentration. The results of analysis of variance showed that the independent effect of species in joint members and numbers of fibers layer were significant at 95% confidence level. The results showed that use of beech wood in comparison with fir wood, composites reinforced by carbon fibers compared to glass fibers, as well as the use of two layers of fiber compared to 1 layer of fibers, illustrated better performance in fabricated joints. The joints made with beech wood and reinforced with 2 layers of composites reinforced by carbon fibers showed the best performance under diagonal compression loading.

Mineral fillers are the second most important elements used in papermaking. Increasing filler content in writing and printing papers without decreasing the mechanical properties is always desired for enhancing the optical and printing properties and cost effective papermaking process. In this study, to increase the filler content in paper, calcium silicate was loaded by in situ precipitation on bleached bagasse fibers. The effect of reaction temperature on the loading and precipitation of calcium silicate on fibers was investigated using ash content measurement, XRD spectroscopy, SEM imaging and EDX analysis. Finally, the effect of treated pulp content on the physical and mechanical properties of pulp was investigated. Ash measurement results showed that calcium silicate precipitation in bleached bagasse fibers was achieved and the amount of calcium silicate loading increased with increasing the reaction temperature. XRD spectroscopy confirmed the formation of calcium silicate and calcium carbonate, and their precipitation in cell walls, lumen and interior spaces of the bleached bagasse fibers was confirmed by SEM imaging. The precipitated minerals on the fiber surface consisted of particles with various diameters. The EDX analysis confirmed the presence of silica and calcium in the treated fibers. With the constant basis weight of 80 g/m2, brightness and apparent density increased significantly, however the paper strength decreased by increasing the content of treated fibers in handsheet paper.

The aim of this study was to solve the environmental problems caused by bleaching of bagasse pulp using sodium hypochlorite in Pars paper mill. For this purpose, ECF bleaching was used by applying OQPDEP sequence. The properties of bleached paper were compared to the bagasse unbleached paper as control and the properties of paper made from bagasse bleached pulp by EH sequence. The results showed that increasing the oxygen delignification time of bagasse pulp from 30 to 120 minutes had no significant effect on paper brightness, but paper density, burst and tear indices decreased. Pulp bleaching by O1QP3D (EP) sequence compared to bagasse unbleached paper led to the paper brightness of about 75% ISO that is about 5% ISO more than the commercial bleached paper. Paper strengths were similar to commercial paper made of soda bagasse and the national standard of Iran (ISIRI 4120). Soda pulp bleaching using O1QP3D (EP) sequence has led to acceptable physical, optical and mechanical properties in addition to environmental benefits such as reduced pollution. Therefore, it is recommended to replace the current bleaching method of in Pars paper mill by new sequence.

In this research, the effect of cellulose nanocrystals on the applied properties of wood cement composite panels was investigated. Variable factors are the percentage of nanocrystals (five levels of 0, 0. 1, 0. 2, 0. 5 and 1%), the weight of cement and also the ratio of mixing wood chips with cement in three levels (1 to 3, 1 to 3. 5 and 1 to 4) dry weight of cement. In this research, poplar wood and Portland cement type 2 have been used. In total, 15 treatments and 3 replicates for each treatment were made. Preparation of sample were in accordance with the standard (DIN/EN 634) and measurement of physical and mechanical properties including flexural modulus, modulus of elasticity in accordance with the standard (DIN/EN 310), internal adhesion in accordance with the standard (DIN/EN 319), thickness swelling after 2 and 24 hours of immersion in water was performed according to the standard (DIN/EN 317). Increased cellulose nanocrystals improved physical and mechanical strength. SEM microscopic images were taken from the samples to examine the microstructural properties of the composite. it was found that by adding cellulose nanocrystals, an improvement in the disintegration of nanocomposite materials and as a result, an increase in mechanical and physical properties are observed.

The aim of this study was to identify and compare the chemical compounds in heart wood and bark of mulberry tree. For this purpose, the samples were randomly selected from heart wood and bark of mulberry tree in Nowshahr's forest region. Then, wood powder and ash were prepared using TAPPI standards test methods. For metallic ions measurement, first the mineral compound of ash was dissolved in 65% nitric acid and for identification by atomic absorption method. The results showed that zinc ion in heart wood of mulberry tree was more than bark, but manganese and iron ions were lower and cupper ion was the same. Then extractives were separated from wood powder by acetone and extractives residue werte transferred to glass vial and BSTFA reactive agent was added. After samples were prepared, theses samples were injected to GC/MS device for it analysis. Identification of compounds was done by retention time of each compound, calculation of Quats index and Adams table. The result of GC-MS showed that there exist 30 compounds in bark of mulberry tree, that beta-Tocopherol(40. 86%), bis (2-ethylhexyl)phthalate(11. 2%), 9, 12-Octadecadienoic acid(9. 12%) and Triphenyl phosphine(9. 82 were among important components. 93 components were identified in heart wood of mulberry tree among them resorcinol(79. 47), methyl diphenyl methane(12. 06%), p-xylene(0. 06%) and gibberllin A3 (0. 15%)di-limonene, were important components. These compounds can be very important in durability of this wood. Comparison of chromatograms showed that 1, 2-benzenedicarboxylic acid exists as a common components in heart wood and bark of mulberry tree.

The aim of this research was to investigate the effect of fiber reinforced polymer (FRP) on the strength of T-shaped wooden joints under tension load. In this regard, T-shaped joints were fabricated with beech and poplar species and were reinforced with 1 and 2 layer of carbon and glass fiber reinforced epoxy and vinylester polymers. Joint members were assembled using wooden dowels and polyvinyl acetate adhesive and then withdrawal strength of reinforced joints were studied. Results of analysis of variance showed that the independent effect of species of joint members, resin type and number of fiber layers at FRPs was significant at 5% level. Results have indicated that withdrawal strength of joints fabricated with beech species was more than the poplar wood. The investigation of the effect of number of layers showed that the withdrawal resistance of the joints reinforced by two layers of carbon and glass fibers was more than one layer. Results of FRPs investigation indicated that use of epoxy matrix in comparison with vinyl ester matrix exhibited better results. In addition, carbon fibers have shown better performance than glass fiber as reinforcing agents. According to the results, the best treatment was the joints of beech wood and reinforced by composites with epoxy matrix and reinforced with two layers of carbon fibers.