فصلنامه جنگل و فرآورده های چوب
سال هفتاد و ششم شماره 1 (بهار 1402)

The SO2-ethanol-water (SEW) fractionation process is one of the most effective and high-performance platforms for biorefining lignocellulosic materials. Determining the most appropriate percentage of chemical compounds in the cooking liquor can increase process performance. The objective of this study was to investigate the effect of ethanol concentration in SEW cooking liquor on the properties of Pinus eldarica pulp. To achieve this, different ethanol concentrations (26-74%, w/w) in combination with varying percentages of water and fixed 12% SO2 were considered. Cooking was conducted in a laboratory digester at a maximum temperature of 135°C for 60 minutes for all treatments. The results showed that increasing the ethanol concentration to 53% decreased the pulp yield, but increasing it further to 74% increased the pulp yield. The kappa number of the pulp decreased as the ethanol concentration increased, but with a further increase in concentration, this was reversed. A slight increase in the pH of the cooking liquor (due to the increased ethanol concentration) significantly decreased pulp brightness. According to the selectivity curve, the best ethanol concentration used in the SEW process was 41%, which was consistent with the concentrations of 43.5% and 44% reported previously

The application of chelating agents to increase the efficiency of hydrogen peroxide is important in various related processes. Synthetic chemicals such as ethylenediaminetetraacetic acid (EDTA) are commonly used in these processes. The feasibility of using natural and environmentally friendly products instead of synthetic materials is an important and interesting subject. In this study, the performance of hydrogen peroxide in the deinking process was considered and the use of chitosan as a natural chelating agent in the deinking process of waste newspapers was investigated. The results showed that hydrogen peroxide bleaching along with the deinking process had a positive impact on the optical properties and reduced the burst and tear indices with no effect on the tensile and fold strengths. Chitosan, similar to the EDTA chelating agent, improved brightness, whiteness, dirt removal, and metal ion absorption in comparison with the treatment without a chelating agent. EDTA performs better than chitosan in removing ink from the pulp. Furthermore, in comparison to the treatment without a chelating agent, both chelating agents improved tear and burst indices, but had no effect on the fold and tensile strengths. The current research can be a small but promising step in using natural materials, such as chitosan biopolymers, instead of synthetic chelating agents, such as EDTA.

In this study, we investigated the effects of glass fiber-reinforced polymers (GFRP) on the withdrawal capacity of wood, lag screws, and steel nails in cross-laminated timber (CLT) made from poplar (Populus alba). We reinforced CLTs with bidirectional GFRP wrap with a grammage of 600 g/m2. The specimens were 75 mm ×75 mm in length and width, and their thicknesses varied depending on the GFRP layers. We used two-component polyurethane glue at a rate of 300 g/m2. ANOVA results showed that the number of GFRP layers had a significant effect on the withdrawal resistance of nails and lag screws (P<0.05). By increasing the number of GFRP layers in CLT, the withdrawal resistance of the nails, wood screws, and lag screws increased by 280.4%, 29.2%, and 83.3%, respectively, compared to the control CLT samples. The withdrawal resistance of the lag screws was greater than that of the wooden screws and nails. Duncan's Multiple Range Test (MRT) results showed that CLT should be reinforced with at least three layers of GFRP to significantly increase the withdrawal resistance of nails. To significantly increase the withdrawal resistance of lag screws, CLT should be reinforced with at least one layer of GFRP or by three layers for further significant reinforcement.

Carboxymethyl cellulose (CMC) is a water-soluble polymer that has many applications in various industries, including pharmaceuticals, food, and oil. There are various raw materials and sources available for the production of CMC, one of which is the important material bagasse. Considering that bagasse contains 30-40% cellulose, it can be considered a cheap and accessible source of CMC. In this study, bagasse was first converted into brown pulp using the soda process and then bleached using sodium hypochlorite and hydrogen peroxide to produce alpha-cellulose using the cold soda method. Finally, CMC was obtained. The alkalinity percentage is an influential factor in the cost and quality of the produced CMC. In this study, alpha-cellulose was produced from bagasse pulp under different alkaline conditions (20, 25, 30, 35, and 40%) using the etherifying agent carboxymethyl mono chlorine acetic acid (MCA). The degree of substitution (DS), purity, pH, and viscosity of the CMC produced were evaluated. The results showed that the produced CMC with an alkalinity percentage of 30% was comparable to that of commercial and industrial samples. The evaluation of CMC produced by FTIR and XRD analyses confirmed the accuracy of CMC production under all the conditions mentioned above. These results showed that bagasse is a good source for CMC production.

The aim of this study was to compare nanolignin and ionic liquid (IL)-treated lignin as new compatibilizers in Wood-Plastic Composites (WPC). For this purpose, lignin was extracted from black liquor and modified with [Emim][OAc]. Then, the modified lignin was used as a compatibilizer in the WPC.  Nanolignin was prepared by an acidic method, and its performance was compared to that of ionic-liquid-treated lignin as a compatibilizer in the composites. Nanolignin and ionic liquid-modified lignin at the same levels (1, 3, and 5 wt%) were added to the wood flour and polypropylene mixture, and WPCs were manufactured using the hot press method. In the next step, all physical and mechanical properties of the prepared panels were analyzed using standard methods. FTIR analysis indicated that modification of lignin by an ionic liquid can change some chemical bonds and even produce new bonds.  However, the chemical structures of the virgin lignin and nanolignin were similar. The physical and mechanical properties of the prepared composites indicated that the addition of both forms of lignin significantly increased the dimensional stability, bending properties (flexural modulus and flexural strength), and impact strength of the composites. Based on the findings of this research, IL-treated lignin exhibited better physical and mechanical results as a coupling agent in wood plastic composites compared to nanolignin; thus, the composites with 5 wt% have the highest mechanical strength and dimensional stability among all lignin-containing samples.

Forest fires are a natural part of the ecosystem, but their uncontrolled spread can result in severe economic and environmental damage. Therefore, it is vital to take measures to prevent and manage their spread. However, given the intricate and complex nature of fires, studying real fires in their environmental context can be challenging, if not impractical. As an alternative, researchers can use computer simulation models based on field studies to better understand fire behavior and its effects on the environment. The FARSITE simulator, based on the Rothermel model, was used to conduct numerical simulations of fire spread with respect to fuel, topography, and weather conditions such as humidity. Simulation results showed that the Sorensen and kappa coefficients were at their highest at 0.80 and 0.77, respectively, in air humidity scenarios; with average values of fire spread rate, flame length, and fireline intensity being 0.58 m/min, 0.54 m, and 74.54 kW/m, respectively. Based on these results, it can be concluded that increasing air humidity is a natural way to prevent fire spread. Furthermore, numerical studies and simulations of fire behavior and spread are appropriate alternatives to experimental studies in this field due to their lower costs and fewer limitations.

Botanical gardens are places where different types of forest and non-forest plants are grown for research, education, and tourism. This research was conducted from the beginning of 2016 until the beginning of 2022 at the Nowshahr Botanical Garden. The experiment was conducted in a randomized complete block design with eight treatments in three replicates. The treatments consisted of several species of Rosaceae shrubs, including apple (Malus orientalis Uglitzk. ex Juz.), pear (Pyrus kandovanica Ghahreman, Khatamsaz, & Mozaffarian), pear (Pyrus mazanderanica Schonb.-Tem), black hawthorn (Crataegus melanocarpa M.B.), red hawthorn (Crataegus microphylla K. Koch.), thornless forest plum (Prunus divaricata Ledeb.), spiny forest plum (Prunus spinosa L.) and forest parsnip (Mespilus germanica L.). Seedlings of the Rosaceae shrub species from the Hyrcanian forests were collected from their main habitat at the heights of Mazandaran Province and planted in Nowshahr Botanical Garden at an elevation of 24 m below sea level. The results of the tests and comparison of the averages using the least significant difference (LSD) test method showed that there was a significant difference in the growth of the species compared with the change in altitude. The highest growth in collar diameter was observed in both hawthorn species (Black Velik and Red Velik), and the growth of hawthorn species was associated with fertility in the first five years of the study. Therefore, hawthorn species were the most compatible treatments in terms of their establishment in response to altitude changes.

The proper spacing for planting stands is of special importance in producing well-shaped, high-quality trees with straight trunks and few knots, as well as in meeting wood production needs. In this study, the wood production performance of five successful clones of Populus nigra L. was tested at different planting spacings. Initially, a sufficient number of cuttings were obtained from the clones, and seedlings were produced in the nursery. Then, 81 one-year-old seedlings from each clone were planted at three different spacings (2×3, 2×2, and 2×1 m) and in three replicates with a randomized complete block design as split plots. Vegetative characteristics such as diameter at breast height (DBH) and total height were measured annually, and the current and average annual increments of DBH, height, and volume were calculated. The damage caused by Phloeomyzus passerinii Sign., Paranthrene tabaniformis Rott., and Monosteria unicostata (Muls & Rey) attacks was also recorded. The results showed a statistically significant difference in vegetative variables of volume per ha and average production among the different planting spacings and clones. The P.n.62/154 clone had the greatest increment in volume per ha, and the highest average yield of wood production per ha after three years was at a spacing of 2×1 m and in the P.n.62/154 clone. The P. n.62/154 clone at 2×1 m spacing is recommended for short-term exploitation and at 2×2 m spacing for medium-term exploitation. Pest investigation showed that the P. n. betulifolia 17/13 clone had the greatest damage to pests at a spacing of 2×3 m, with an 18.52% frequency. The P. n.62/154 clone at a planting spacing of 2×1 m with an average wood production of 90.88 m3 ha-1yr-1 for short-term exploitation and at a planting spacing of 2×2 m with an average wood production of 44.36 m3 ha-1yr-1 for medium-term exploitation are recommended in Markazi Province.