مجله صنایع چوب و کاغذ ایران
سال سیزدهم شماره 3 (پاییز 1401)

The purpose of this study is to evaluate the environmental effects of SMF and GMF fluting paper production of Mazandaran Wood and Paper industries using the Life Cycle Assessment (LCA) method. Statistics and information required for this research were obtained through interviews with engineers and experts of the industries. The findings show that in section on the Life cycle inventory (LCI), the amount of water consumed and the emission of carbon dioxide have a greater share than other materials. Also, by examining the intermediate indices, it was found that among 15 groups of effects (carcinogenicity, non-carcinogenicity, mineral respiration, ionizing radiation, ozone depletion, organic respiration, aquatic toxicity, soil toxicity, soil acid/nutrient, occupation Earth, aquatic acidification, swamping, global warming, non-renewable energy and mineral extraction (aquatic toxicity category and non-renewable energy index) have the largest share. Findings from the assessment of damage in four categories of damage (human health, ecosystem quality, climate change and resources) show that the share of SMF fluting paper 155.08 percent and the share of GMF fluting paper 100 percent and the share Each is weighted in SMF 0.81pt and GMF 0.67pt. Also cumulative exergy demand in SMF fluting paper 38864.9 MJ and in GMF fluting paper 25873.53 MJ and the share of each in percentage in SMF fluting paper 150.21 percent and in GMF fluting paper 100 percent. The results showed that the production of GMF fluting paper has less environmental effects on the environment than the production of SMF fluting paper.

The aim of this study was to investigate the effect of microwave heat treatment on the physical and mechanical properties of composites made of wood flour, nanosilica and HDPE. For this purpose, nanosilica was used in four levels of 0, 1, 2 and 3%. First, the materials were mixed together in a twin-screw extruder and then ground into wood-plastic samples by injection molding machine. Also, to modification the properties of the composites, a standard microwave radiation with a power of 900 watts was used. The samples were subjected to physical and mechanical tests after applying microwave radiation. The results showed that with increasing nanosilica up to 3%, the modulus and flexural strength increased and the impact resistance, water absorption and swelling thickness of the samples decreased. The overall results showed the positive effect of microwave radiation on improving the adhesion in the interface area and increasing the modulus and flexural strength and reducing the water absorption of the samples. Also, the impact resistance of the samples was reduced by applying microwave treatment. These results were also confirmed by electron microscope images.

The properties of wood composite products are due to the control variables of factory machines. Identifying these sensitive places is of particular importance, because it allows the operator to be able to adjust the production line and product quality in a completely engineered way. Also, it allows operator to have a more detailed study of material and process behavior. Factory available data are including variables of moisture content of chips, chips density, density Mat, material temperature The amount of glue used in percent, the amount of glue used in kilograms, fiber moisture and press speed, and also properties of density, flexural modulus, modulus of elasticity, internal bonding, board moisture and thickness swelling. The effect of input variables on each of the properties of fiberboard was determined by artificial neural network method. The results show that all of the input variables have affected on the output properties of fiberboard and the order in which the influential variables are depends on the type of properties. The effect of variables such as density Mat is almost greater than other variables. Some input variables, such as the, the amount of glue used in kilograms, have less effect on the properties of fiberboard with medium density, and this variable is considered constant in the production line of some factories. The high correlation between the prediction value and the actual value of the output and its low mean absolute percent error indicates the high validity of the prediction that have a high value of 0.9 and less than 9%, respectively.

In this study, the ability to bleaching hemicellulose-deinked pulp was investigated in comparison with conventional chemical method. Initially, the mixed recycled pulp pre-treated with hemicellulase enzyme at different levels of usage, treatment time and pH values (under other constant process conditions) was bleached and experimental runs included H2T3 (usage 0.2% (based on dry weight of recycled pulp); Treatment time 60 minutes and pH range 6.5-7) and H3T2 (usage 0.5% (based on dry weight of recycled pulp); Treatment time 50 minutes and pH range 6.5-7) were selected as the best treatments. Then, the selected pulps were bleached using hydrogen peroxide under constant process conditions and their bleachability was compared with conventional chemical pulp. Based on the results achieved, the bleachability of hemicellulose-deinked pulps was better than that of chemically deinked pulp, and the resulting papers had a higher brightness and whiteness as well as less yellowness, but the opacity of these papers was decreased during bleaching. Also, pre-treated pulps with hemicellulase showed the papers with higher tensile and burst indices after bleaching stage so that for H2T3 and H3T2 enzymatic runs, the increase in tensile index was 13.22% and 12.59%, and in burst index was 3.66% and 6.22%, respectively. While the tensile and burst indices for chemically deinked pulp after bleaching was improved by 10.17% and 16%, respectively. Also, the reduction in paper tear index for H2T3 and H3T2 enzymatic runs after bleaching was 12.45% and 8.06%, respectively, compared to chemically deinked pulp (4.44%). Based on the overall results obtained by comparing the quality properties of papers made from different pulps bleached with hydrogen peroxide, H2T3 run has resulted in more bleachability and much better optical and strength properties.

SStarch derivatives are as the most common additives required in the paper industry to increase paper strength, and for other various applications. Although both starch addition to the stock (internal application) and surface treatment of the board with starch (surface application) have limitations in applications and also different effects on paper products properties. But both of mentioned methods can be performed with the purpose of improving the mechanical properties of recycled linerboard. Therefore, in the current research, the effect of adding cationic starch to the pulp and also using the same amount of cationic starch for surface application on mechanical properties of recycled linerboard and water absorption (Cobb test) were comparatively evaluated. The results showed that, surface treatment of the paperboard clearly caused 30-45% increment in bending strength. Furthermore, internal application of cationic starch totally showed higher tensile strength index in comparison with surface application of cationic starch. However, there was not significant difference between paper tear index value by applying cationic starch in papermaking.

In recent years, the use of adsorbents for pre-treatment process has been the focus of attention. In this survey, the efficiency of pollutants removal and pre-treatment of cellulose industry’s wastewater with COD/BOD5 equal to 4.6 was investigated by perlite adsorbent. In this study, the performance of different amounts of perlite adsorbent was investigated in 6-24 h. The highest removal of indicators was observed after 24 h in the sample containing 12.5 gr/L perlite showing 48%, 76% and 47% reduction in COD, TSS and TDS respectively. According to the statistical analysis, the adsorbent amount and the adsorption time had a significant effect on the reduction of wastewater turbidity and COD, while TDS and EC of the wastewater was only affecting by the adsorption time which can be considered as a consequence of limited accessibility of perlite as well as adsorption and kinetic limitations. Finally, it can be concluded that perlite as a low-cost and environmentally friendly adsorbent can play an important role in cellulose industry effluent pretreatment by considerable decline in pollutants in the wastewater stream.

In this study, bending performance of the WPC profiles of Asre Honar company were measured, then were predited by finite element method (FEM) with ANSYS software to decrease the cost and time of measurement. Therefore, the bending strength of small control specimens with a span length of 180 mm were firstly measured. Accordingly, their bending modulus of elasticity (MOE) and Poisson's ratio of 0.3 were used as input data for prediction. Therefore, four types of hollow and solid WPC profiles with span lengths of 180 and 450 mm were tested under three-point bending loading with a Hounsfield 0308 testing machine with a loading rate of 5 mm/min. Subsequently, their MOR and creep values were measured and compared with those predicted by the FEM. The results of the analysis of variance (ANOVA) Table showed that the main effect of profile types on MOR was statistically significant. Furthermore, the main and the interaction effects of the span lengths and profile types on MOE were statistically significant. The investigation of the main effects revealed that MOR and MOE decreased by 8.8% and increased by 17.7%, respectively by raising the span length from 180 to 450 mm, and also they altered by 33.1% and 24.2% with the change in profile types. In addition, the interaction effects showed that MOR and MOE values changed by 43.9% and 66.6%, respectively with the simultaneous change of the span lengths and profile types. The results indicated that the FEM predicted the MOR values with a mean absolute percentage error (MAPE) of less than 3.03% and their corresponding creep with a MAPE of less than 15.25%. According to the satisfied MAPE of FEM, it could be suggested as an efficient method for predicting the bending properties of these products.

Pinus taeda is one of the fastest growing species with high wood production capacity. Due to the afforestation of this species in Gilan province, which can be a good alternative to some other imported fast growing species.The aim of this study is to investigate of possibility of using Pinus taeda wood instead of four common species of poplar (Pulpous sp.), Tehran pine (Pinus eldarica), Abies (Abies sp.) and Sasna (Pinus sylvestris). For this purpose, physical and mechanical properties of five species were measured and statistical analyzes were performed. The results showed that Pinus taeda has lower density, water absorption and volumetric swelling than the other four species. Regarding mechanical properties, the results showed that Pinus taeda, with its lower density than other species, has moderate mechanical strength. The ability of Screw and Nail Withdrawal Strengths for Pinus taeda in parallel and perpendicular directions to the grains was not much different from other species. Also, the resistance of mortise- tenon and dowel joints for Pinus taeda was higher than other species and there was a significant difference with them. According to the obtained results, Pinus taeda wood with low density and suitable mechanical properties can be a good alternative for some imported fast-growing species and is also recommended for afforestation and wood cultivation in different parts of the country.

In this research the effect of additive of Chlorophytum comosum (C. comosum) plant extract on physicochemical, structural properties and shear strength of urea formaldehyde (UF) resin was investigated. C. comosum leaf extraction was performed according to the method of Bondareva et al. (2017) and was added to UF adhesive at two levels of 5 and 10%. The properties of adhesive such as solid content, gelation time, pH, density and free formaldehyde were measured before and after adding the extract. To identify the possible chemical structures of the reaction between the components of the adhesive and the extract and to investigate the reactions' bonds and intensity, matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI ToF) and Fourier transform infrared spectroscopy respectively, were performed. The shear strength test of the plywood was used according to EN 314-2. Based on the results of physicochemical properties, the formation of multiple hydrogen bonds between the active functional groups of the adhesive and the extract led to an increase in intermolecular forces and an increase in the cohesive strength of the adhesive, thereupon the amount of free formaldehyde in the adhesive decreased by 16.67% with the highest amount of extract. The possible chemical structures of the reaction of some active functional groups of the extract with UF adhesive were confirmed by MALDI TOF mass spectrum. The addition of C. comosum extract weakened the absorption intensity of UF adhesive' peaks, which indicates that the extract of active groups reduced the formation of chemical bonds, including methylene and ether bonds in the adhesive. The significant improvement in shear strength of plywood obtained from adhesives containing the extract can be attributed to the quality of cross joints and increase of adhesive density so that the highest shear strength of plywood was 2.07 MPa with adding 10% of the extract.

This research was carried out with the aim of making a stringer of wooden spiral stairs using laminated wood product from poplar wood and achieving an optimal connection to convert the stringer to smaller dimensions in order to achieve a suitable design for the construction of wooden spiral stairs. For this purpose, 3-layer plywood of poplar was made using two-part polyurethane glue with a surface layer thickness of 0.5 mm and a middle layer of 2 mm in dimensions of 120 x 120 cm, and then the produced plywood panels were used to make the desired laminated product. Mechanical properties and failure modes of the product were investigated. Then, 5 types of end to end joints including finger joint, tail joint, half and half, diagonal and modified diagonal joints were designed for the stringer of the wooden spiral stairs and made in the dimensions of length 65, width 20 and thickness 2.1 cm and subjected to out of plane bending test. Modulus of elasticity of the stringer in the in plane bending test was obtained as 1598 MPa, 2441 MPa, 1669 MPa, 1047 MPa, 957 MPa and 652 MPa, respectively for control sample, modified diagonal joint, diagonal joint, half-and-half joint, finger joint and tail joint. In addition, modulus of rupture of the stringer in the in plane bending test was obtained as 32 MPa, 27 MPa, 23 MPa, 19 MPa, 12 MPa and 13 MPa, respectively for control sample, modified diagonal joint, diagonal joint, half-and-half joint, finger joint and tail joint. The result of one- way ANOVA showed that there is a significant difference among bending strength and modulus of elasticity of the stringers at 99% confidence interval (α≤0.01). According to the results, the stringer with modified diagonal joint would be the most suitable alternative in wooden spiral stair.