Iranian Journal of Wood and Paper Science Research
Year:2021 | Volume:35 | Issue:4 (73)|Papers Count:7

Fiber Reinforced Polymer (FRP) has become one of the most popular material in the reinforced, repair and rehabilitation of structure due to its ease of application and the special physical and strength characteristics. The aim of this research was to investigate the structural performance of corner joint reinforced with fiber reinforced polymer (FRP) composite under diagonal tension load. Constructed joints from two wood species; beech (Fagus orientalis) and fir (Abies alba), were reinforced with FRP composites including one and two layers of carbon and glass fibers and then they were tested under diagonal tension load. The miter corner joints were made using wooden pin and polyvinyl acetate adhesive. The fibers lay-up was done manually. Epoxy resin was used as a polymeric matrix. Result of investigation indicated that the samples fabricated using beech wood in comparison with fir exhibited better results. In addition, glass fibers have shown better performance than carbon fiber as reinforcing elements. Inspection of diagonal tension specimens after failure have indicated that using FRP on the surfaces of Lshaped miter prevents joint opening. However, failure was occurred at the joint by increasing of the load and vertical displacement and wood weakness in tension perpendicular to the grain and shear parallel to the grain at dowels location due to stress concentration. The results showed that the miter corner joint made with beech wood and two layers of glass fibers FRP had the highest stress carrying capacity.

This study was carried out to determine the effect coating with polylactic acid-chitosan complex on the packaging paper by two methods of mixing and grafting. For this purpose, handsheet (80 g/m2) was made using long fibers collected from Mazandaran Wood and Paper Factory. Poly lactic acid, chitosan and nanocytosis with the concentration of 1 wt. %, were prepared by dissolving in chloroform and 1% acetic acid, respectively. In both methods, three layers coating was applied. Then, coated samples were dried in oven. In the mixing method, polylactic acid and chitosan were mixed and then applied on base paper. In the grafting method, by chemical modification of chitosan and polylactic acid, 0. 01 g of EDC (N-(3-dimethy laminopropyl)-N/-ethylcarbodiimide hydrochloride), 0. 1 g of Span 80 and 0. 047 g of HOBT ( 1-Hydoxy benzotriazole) homogeneous solution were prepared and applied on a paper surface. Finally, barrier and mechanical properties including contact angle, water absorption, air permeability and burst strength were measured respectively. The results showed that papers which were coated with grafting method, using three layers of coating (P3nCs3) had the highest air permeability resistance compared to the mixing method. Control sample showed minimum air permeability resistance. Water absorption decreased in coated samples by mixing method compared to grafting method and grafting method further reduced water absorption. Contact angle increased in coated samples by the grafting method compared to the mixing method.

Biodegradable magnetic nanocomposites of cellulose fibers have been widely used in adsorption of heavy metals from water. In this research, nano magnetic absorbent papers were produced by commercial kraft long fiber (NMP), magnetic fibers with 1% gluconic acid (NMP / GA 1%), nanocrystalline cellulose (MNCC) as well as carboxymethyl cellulose (MCMC), and the adsorbents were used to remove heavy metals; lead (Pb) and nickel (Ni). The nanocomposites were evaluated by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and sample vibration magnetometer (VSM). X-ray diffraction patterns showed that magnetic fibers and composites were successfully produced and the nano magnetite peaks were observed in all samples. Examination of nano magnetite and cellulose nanocrystals showed that most of the particles were in the range of 1-19 and 1-65 nm, respectively. The highest magnetic saturation was related to the nanocrystalline cellulose magnetic composite. Adsorption samples were examined by a microwave plasma atomic emission spectrometer. The results of lead and nickel adsorption test showed that the NMP / GA 1%, MCMC and control sample adsorbents had highest and lowest amount of lead and nickel adsorption, respectively. Lead metal also has a higher adsorption than nickel with all the adsorbents.

In this study, the effect of graphite and two modified graphite materials was investigated in reducing formaldehyde emission from medium density fiberboard (MDF). For this purpose, expanded graphite (EG) was synthesized from graphite (G) and modified expanded graphite (MnO2-EG) was produced through the intercalation process of expanded graphite with manganese dioxide. Thus, three graphite materials were prepared for resin treatment. Molecular tests including X-ray diffraction (XRD) and X-ray diffraction spectroscopy (SEM-EDS) were performed to determine their molecular properties. In addition, the differential scanning calorimetry (DSC) test was performed to evaluate the thermal behavior of the resin under the influence of any graphite materials as an additive. The additives were added to urea formaldehyde resin at three levels of consumption of 1, 2 and 3%, and then medium density fiberboard (MDF) was made from glued fibers with a density of 750 kg/m3. After making the board, the formaldehyde emission test was performed by desiccator method. Overall, MnO2-EG showed better results than control and two other graphite treatments. The best performance was resulted using MnO2-EG at 3% and formaldehyde emission was reduced by about 61%. It seems that the formaldehyde molecules absorbed on the expanded graphite layers which are exposed to oxidation by manganese dioxide molecules. On the other hand, as the DSC test showed, the highest enthalpy reaction occurred in MnO2-EG-incorporated resin, indicating the increased chemical reaction with formaldehyde molecules in the UF resin structure.

This study was carried out to investigate the effect of two board density levels of 800 kg/m3 and 1100 kg/m3 and two levels of industrial wood to cement ratios of 25: 75 and 35: 65 on mechanical and physical properties of wood cement composites. Boards were produced and then the density of boards were calculated. The experimental boards were subjected to modulus of elasticity and modulus of rupture tests in accordance with EN 310. Internal bonding was evaluated according to EN 319. Water absorption and thickness swelling were evaluated after 2 and 24 hours immersion in water according to EN 317. Fire resistance was evaluated according to ISO 11925. Results indicated that bending properties of the boards, including modulus of elasticity and modulus of rupture, and internal bonding increased at higher density. That was attributed to the high compression and improved binding between fiber and cement matrix. Modulus of elasticity increased significantly as cement content was raised. Modulus of rupture values were inversely related to cement content. Increasing wood to cement ratio led to low internal bonding because the low amount of cement can be insufficient to cover the wood particles for effective bonding to resist the tensile forces applied during internal bonding test. As the board density increased, dimensional stability increased. Variations in the wood to cement ratio have been reported to significantly affect the dimensional stability of specimens. Water absorption and thickness swelling increased with the increase in wood to cement ratio. Fire resistance of specimens improved when the board density and cement content increased. All of the mechanical properties of boards produced in this study satisfied the EN 634-2 requirements.

Sulfide ions (S-2) derived from Na2S remaining in kraft black liqueur are the source of H2S gas production in recovery cycle in the Kraft pulping. In this study, we tried to prevent the production of H2S by removing the mentioned ions from black liquor using synthesized adsorbents (Cu-PAC and Cu-BWP100). The adsorbents were produced by immersing activated carbon (PAC) powder and 100 mesh beech powder (BWP100) in 0. 1 M solution of CuCl2. The adsorbent properties were measured before and after copper ion loading by FTIR, BET and SEM-FEI analyses. Finally, the performance of these adsorbents in the removal of S-2 from black liquor with three levels of sulfide (22%, 20 and 18) was investigated. The results of FTIR, BET and SEM-FEI analysis showed that Cu+ 2 was located on the surfaces of raw organic material without any change in their structure. Experimental data for the Cu-PAC adsorbent showed that it was more agreement with the Freundlich equation and follow to the pseudo-second-order kinetic model, whereas for Cu-BWP100 adsorbent was more consistent with the Langmuir equation and adherence to the pseudofirst-order kinetic model. The Cu-PAC adsorbent had the ability to remove 79. 93% and Cu-BWP100 at 60. 03% of S-2 from black liquor. The Cu-PAC, with its higher specific surface area, has a higher ability to remove S-2 from the black liquor than the Cu-BWP100. In general, the mentioned adsorbents will have a high ability to reduce H2S production by eliminating S-2.

In this study, the strength properties of plastic wood nanocomposite produced using 5 levels of cellulosic residues (bagasse, corn stalk, rice straw, sunflower and canola stem), three levels of nanomaterials (carbon nanotubes, nano silica, nanoclay) and urban polymer wastes (PP polypropylene and HDPE, etc. ) were investigated. In order to chemically bind the wood / polymer fiber composites, chemicals and reinforcement, coupling agent was used. Extruders and hot presses were used to fabricate the composites. The mechanical properties and bonding strength of the composites were measured using relavent DIN test methods. The results showed that the use of HDPE polymer wastes increased tensile strength, flexural modulus and impact resistance compared to polypropylene wastes. Regarding the use of agricultural residues in the production of wood-plastic composites, in general, the results have shown that the addition of agricultural residues in several types of plastic wood has significantly improved the bending and tensile properties. Among them, the bagasse has a significant advantage over other lignosullose materials. The use of polymer waste and agricultural residues and using nano-silica has shown the best results in strength properties. In general, the results have shown that the use of agricultural fiber residues as reinforcement in plastic woodcomposites improved the expected mechanical properties.