Magazine covers
Volume 40, Issue 4 , December 2025
Editorial
Volume 40, Issue 4 , December 2025
Composite Wood Products
Composite wood products
Alireza KHAKIFIROOZ; Ahmad Samariha; Hirsa Jouya
Abstract
Background and objectives: Given the increasing use of nanocomposites in various industries, improving the mechanical and physical properties of these products is of particular importance. Nano calcium carbonate as an effective reinforcing agent can help improve the performance of poplar flour and recycled ...
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Background and objectives: Given the increasing use of nanocomposites in various industries, improving the mechanical and physical properties of these products is of particular importance. Nano calcium carbonate as an effective reinforcing agent can help improve the performance of poplar flour and recycled polypropylene nanocomposites. This research investigates the effect of the dosage of calcium carbonate nanoparticles in the nanocomposite mixturr on the mechanical properties of these nanocomposites. The main objective of this research is to evaluate the effects of the size and amount of nano-calcium carbonate on the modulus of elasticity, tensile strength, and other mechanical properties of nanocomposites. The results of this study can help develop lightweight and durable products in the packaging, automotive, and other industries, and provide a solution for the optimal use of recycled materials.Methodology: For this purpose, polypropylene (at three levels of 50, 60, and 70%), poplar wood flour (at three levels of 30, 40, and 50%), nano calcium carbonate (at four levels of 0, 1, 2, and 3% by weight), and maleic anhydride grafted polypropylene at a fixed level of 3% were mixed using a twin-screw extruder, and standard test specimens were made using injection molding. Then, mechanical properties including tensile and bending strength, tensile and bending modulus, impact strength, and hardness were measured.Results: The results related to the F-value and significance level showed that the effect of wood flour content on mechanical properties including tensile and bending strength, tensile and bending modulus, impact strength, and hardness was significant at a confidence level of 95%. Additionally, the effect of nano calcium carbonate on tensile and bending strength, bending modulus, and hardness was also significant at 95% confidence level, while bending modulus and impact resistance were not significant at this level. The interaction effect of flour amount and nano calcium carbonate was not significant on all strength at the 95% confidence level.Conclusion: The results of this research show that increasing poplar wood flour from 30 to 50 percent has a significant effect on the mechanical properties of nanocomposites, especially increasing tensile and bending strength, tensile and bending modulus, and hardness. This improvement is due to increased adhesion and stress transfer between phases. However, increasing the amount of flour leads to a decrease in impact resistance and greater brittleness of the composite. Adding up to 3% by weight of nano calcium carbonate also improved the mechanical properties, but similar to flour, the impact resistance decreased. Overall, the appropriate selection of the type and number of additives can help improve the performance of nanocomposites, but it is also essential to pay attention to negative effects such as reduced impact resistance.
Physics and Mechanical Wood
Mechanical conversion of wood and wooden fittings
mohammad najafianashrafi
Abstract
Background and Objective: Wood is a unique renewable natural resource that plays a vital role in the socio-economic development of countries. Walnut (Juglans regia) is a durable and mature-trunked tree species found in temperate and subtropical forests of Asia, Europe, and America. In Iran, it is one ...
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Background and Objective: Wood is a unique renewable natural resource that plays a vital role in the socio-economic development of countries. Walnut (Juglans regia) is a durable and mature-trunked tree species found in temperate and subtropical forests of Asia, Europe, and America. In Iran, it is one of the most important wood species, widely used in industries such as furniture, veneer, and construction panels. Therefore, obtaining detailed physical and mechanical characteristics of this species is essential.Materials and Methods: In this study, sampling was carried out from walnut trees in the forests of Barkala village, Kordkuy County (Golestan Province), at an altitude of 1434 meters above sea level. Three healthy trees were randomly selected and harvested. The average diameter at breast height was 51.3 cm, and the average age of the trees was approximately 51 years. Tests were conducted according to ISO 3129 and ASTM D-143 standards for physical and mechanical properties, respectively. Approximately 319 samples were tested for physical properties and 246 for mechanical properties. Physical characteristics examined included oven-dry density, basic density, green density, maximum moisture content, shrinkage, and swelling. Mechanical properties included bending strength, modulus of elasticity, compression parallel to grain, tensile strength (parallel and perpendicular), shear strength parallel to grain, hardness, and cleavage resistance. The samples prepared for mechanical tests were placed in a climate chamber for four weeks at a temperature of 20 degrees Celsius and a relative humidity of 65 percent so that the humidity of all samples during mechanical tests was 12. To perform mechanical tests, a SANTOM 150 testing machine with appropriate load cells for each test located at Imam Mohammad Baqer National University of Skills and Knowledge, Sari, was used.Results: The green, oven-dry, and basic densities were found to be 1.16, 0.63, and 0.54 g/cm³, respectively. Longitudinal, radial, tangential, and volumetric shrinkage were 0.4%, 5.65%, 8.30%, and 14.35%, respectively. Corresponding swelling values were 0.51%, 5.71%, 8.88%, and 15.1%, and the maximum moisture content reached 105.14%. Mechanical properties measured included: bending strength (102.46 N/mm²), modulus of elasticity (10246.02 N/mm²), compression parallel to grain (34.11 N/mm²), tensile strength parallel and perpendicular to grain (146.17 and 9.66 N/mm²), shear strength parallel to grain (11.54 N/mm²), hardness (6622.70 N), and cleavage resistance (1.69 N/mm²). The results obtained show the positive effect of age on the mechanical properties of wood. Of course, factors such as geographical factors and altitude above sea level also have an effect on the physical properties of wood, such as swelling and elongation of wood. Of course, in this study, it was found that the effect of tree age on the mechanical properties of wood has a completely positive effect.Conclusion: The walnut trees from the Barkala village of Kordkuy in Golestan Province showed favorable density and generally superior mechanical properties compared to walnut wood from four other provinces previously studied. This may be due to the higher average age of the trees in this region. Given the strong mechanical properties, this wood is well-suited for use in parquet flooring, furniture, veneer, and construction panels
Research Paper
Pulp and paper
Salman Akhoundzadeh; Mansour Soufi; Seyedeh Ameneh Sajjadi; Mehdi Fadaei
Abstract
Background and Objective: The paper industry, as one of the keys and widely applied sectors in the national economy, has always faced multiple challenges regarding resource consumption, environmental impacts, and social requirements. Achieving sustainability in this industry not only ensures long-term ...
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Background and Objective: The paper industry, as one of the keys and widely applied sectors in the national economy, has always faced multiple challenges regarding resource consumption, environmental impacts, and social requirements. Achieving sustainability in this industry not only ensures long-term survival and profitability but also contributes to reducing the use of natural resources, improving environmental performance, and strengthening the social standing of organizations. The present study was conducted to identify and analyze the fundamental sustainability indicators in Iran’s paper industry, employing the fuzzy cognitive mapping (FCM) method to provide a comprehensive picture of the interactions among key factors and to propose practical strategies for enhancing organizational resilience.Materials and Methods: The research population consisted of 12 experts from the paper industry and academics specializing in sustainability, selected based on criteria such as extensive professional experience, managerial background, and familiarity with sustainability concepts. Initially, through a systematic review of scientific sources and searches in reputable databases, 93 preliminary indicators were identified. Using principal component analysis (PCA), these were reduced to 24 final indicators across three dimensions: Social (employee training and development, employee satisfaction, customer satisfaction, corporate accountability, employee exposure to chemicals and bleaching agents); Environmental (energy consumption, maintenance planning for energy loss reduction, hazardous waste management, recycling capacity, reduction of environmental pollutants, use of recycled materials, sludge management, air pollution, use of gray water, wood consumption); and Economic (production cost per ton of paper, paper product price, company profitability, operational efficiency, paper quality, wastepaper purchase cost, downtime and production stoppages, revenue from by-products, recycling costs). Although the role of government in policy formulation and the enforcement of environmental and social regulations is highly significant, this study primarily focused on internal organizational components that are directly under the control of industrial units. Nevertheless, the influence of governmental policies is indirectly reflected through regulatory and environmental indicators incorporated within the analytical framework. Pairwise comparison questionnaires were then designed to measure the intensity of causal relationships among indicators, and the resulting data were transformed into fuzzy numbers. Finally, using FCM Expert software, the fuzzy cognitive map was constructed, and the degree of influence, dependency, and centrality of the indicators was analyzed.Results: The results revealed that the sustainability structure in the paper industry is shaped around a central core of key indicators that play the most significant role in overall system dynamics. Among these, corporate accountability ranked first with the highest centrality score (14.37), establishing itself as a managerial lever and strategic intervention point. Following this were company profitability (13.78), use of recycled materials (10.92), wood consumption (10.80), and operational efficiency (10.72). These indicators rapidly converged to stable values and were classified as “strong and persistent drivers,” meaning that managerial interventions in these areas can swiftly trigger systemic transformations. In contrast, indicators such as energy consumption, sludge management, and maintenance planning for energy efficiency were categorized as “moderate drivers,” showing slower growth and stabilizing at slightly lower levels, though still exerting substantial long-term influence. Meanwhile, factors like wastepaper purchase cost, production downtime, revenue from by-products, air pollution, and customer satisfaction showed lower centrality, declining early in the iterations and converging to minimal values. This behavior suggests that these peripheral indicators have a weaker role in stimulating the overall network and are more strongly influenced by other components rather than acting as independent change agents.Conclusion: The findings indicate that achieving sustainability in the paper industry requires a phased and systemic approach. The initial focus should be on designing socially responsible policies, improving efficiency, and developing circular economic models. Subsequently, investments in modern energy and recycling technologies can consolidate the path toward sustainability. Ultimately, enhancing peripheral aspects such as cost management, pollution control, and expansion of by-product markets can reinforce the industry’s long-term sustainability and strengthen its position within the national economy.
Research Paper
Nano composite
Mohammad Poodineh; Babak Nosrati; Mohammad Dahmardeh; Saeidreza Farrokhpayam
Abstract
Background and purpose: Nowadays, natural polymers such as cellulose, starch, and polylactic acid (PLA) are used as alternatives to petroleum polymers in various fields. Among them, PLA has been considered as the polymer that has the most structural similarities to petroleum polymers. In this study, ...
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Background and purpose: Nowadays, natural polymers such as cellulose, starch, and polylactic acid (PLA) are used as alternatives to petroleum polymers in various fields. Among them, PLA has been considered as the polymer that has the most structural similarities to petroleum polymers. In this study, PLA was used as the base polymer for foam production. Wood floor as a mechanical enhancer and azodicarbonamide (ACA) was used as a foaming agent. Microcrystalline cellulose (MCC) was used as a nucleating agent.Materials and methods: The PLA foams were prepared by combining wood flour, foaming agent, and nucleating agent in an extruder and then molding using pressing. MCC as a nucleating agent in the production of PLA/wood flour foam with ACA foaming agent was used. Thermal properties of the prepared panels were investigated using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC).Results: The results showed that by increasing the amount of foaming agent to 3% and nucleating agent to 4%, the density of the foam panel was reduced by 52.45%. The decrease in density was accompanied by an increase in porosity, an increase in water absorption, and an increase in thickness swelling at all treatment levels (1 to 3% foaming agent and 1 to 4% nucleating agent). This decrease in density led to a decrease in tensile and flexural strength as well as an increase in impact strength. The results of TGA and DSC tests showed that the use of foaming agent did not change the glass transition temperature of the manufactured foams, but the addition of MCC led to an increase in the glass transition temperature of the foams. Also, the DSC results showed a change in the crystallization behavior of the manufactured foams after the addition of MCC.Conclusion: This study indicated that the nucleation property of MCC was effective in controlling cell growth and reducing pore diameter. Therefore, MCC can be used to produce microcellular polylactic acid foam of acceptable quality. Considering this issue, the present study emphasizes the use of microcrystalline cellulose (MCC) due to its industrial applications, low cost, biodegradability, and environmental impacts.
Research Paper
Chemical conversion
Noureddin Nazarnezhad; Mehran Parastar; Mehran Sinaki
Abstract
Background and Objectives: Nitrocellulose, a key cellulose derivative, is widely used in various industries such as explosives, polymeric coatings, photographic films, pharmaceuticals, and biomedical applications due to its high reactivity, solubility in organic solvents, film-forming capability, and ...
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Background and Objectives: Nitrocellulose, a key cellulose derivative, is widely used in various industries such as explosives, polymeric coatings, photographic films, pharmaceuticals, and biomedical applications due to its high reactivity, solubility in organic solvents, film-forming capability, and controlled combustibility. The applied properties of nitrocellulose are highly dependent on the nature of the cellulose raw material and the nitration conditions. Traditionally, high-purity alpha-cellulose has used as the standard precursor for nitrocellulose production. However, the emergence of cellulose nanofibers (CNF), at nanoscale dimensions, high surface area, and enhanced reactivity, has opened new opportunities for producing modified nitrocellulose with advanced functionalities. Given the fundamental structural differences between alpha-cellulose and nanofibers, investigating how the source material affects the chemical, physical, and thermal properties of nitrocellulose is of significant interest. The aim of this study is to systematically compare nitrocellulose produced from alpha-cellulose and cellulose nanofibers and to evaluate their performance under various nitration conditions.Materials and Methods: Alpha-cellulose was extracted from wheat straw through acid pre-extraction, soda-anthraquinone pulping, TCF bleaching and final sodium hydroxide (17.5%) extraction. Commercial cellulose nanofibers with diameters of 10–50 nm were used. The nitration process was carried out using a nitric acid–sulfuric acid mixture (3:1 v/v) at 30°C for 45 minutes. Three concentrations of nitric acid (20, 40, and 80 mL) were used to examine the effect of nitration intensity. After the reaction, all samples were thoroughly washed and dried. The resulting nitrocellulose samples were evaluated in terms of degree of substitution (DS), viscosity, degree of polymerization (DP), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and burning rate.Results: The nitrocellulose derived from alpha-cellulose (NC) exhibited a higher degree of substitution (DS) compared to that obtained from cellulose nanofibers (NNC). In the NC samples, the DS increased from 1.151 at 20 mL nitric acid concentration to 1.454 at 80 mL, while in the NNC samples, the DS values ranged between 1.088 and 1.182. The viscosity of NC decreased from 359.8 cP to 325.9 cP with increasing acid concentration, whereas the viscosity of NNC samples could not be measured due to their plastic-like behavior. The degree of polymerization (DP) of NC decreased from 311 at low acid concentration to 279 at higher concentration. FTIR spectroscopy revealed a reduction in the absorption intensity of O–H bands within the range of 3200–3600 cm⁻¹ and an increase in the intensity of nitro group bands between 1250–1650 cm⁻¹. Thermogravimetric analysis (TGA) indicated higher thermal stability for NNC, as its main decomposition temperature shifted from 200–230 °C in NC to 240–270 °C in NNC. In the burning rate test, NC samples burned faster, with an average rate of 2.8 mm/s compared to 1.9 mm/s for NNC, demonstrating the higher reactivity and flammability of alpha-cellulose-based nitrocellulose.Conclusion: The type of cellulose precursor plays a critical role in determining the final properties of nitrocellulose. Nitrocellulose prepared from alpha-cellulose, due to its uniform structure and greater accessibility of hydroxyl groups, exhibited higher degrees of substitution and faster burning rates, making it suitable for explosive and coating applications. In contrast, cellulose nanofibers, owing to their nanoscale architecture and larger surface area, produced nitrocellulose with enhanced thermal stability and controlled reactivity, suitable for safer and more advanced uses. These findings can contribute to the optimization of nitrocellulose synthesis and the design of innovative materials for emerging applications in energy, biomedicine, and advanced composites.
Pulp and Paper
Pulp and paper
Hossein Pourkarim Dodangeh; Hossein Jalali Torshizi; Hamidreza Rudi
Abstract
Background and Objective: The accessibility and shortage to virgin pulps and recycled pulps with lower reusing cycles in recent years has led to adverse effects on the quality of recycled paper products which are used for packaging. The use of chemical additives is considered as an effective strategy ...
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Background and Objective: The accessibility and shortage to virgin pulps and recycled pulps with lower reusing cycles in recent years has led to adverse effects on the quality of recycled paper products which are used for packaging. The use of chemical additives is considered as an effective strategy to improve properties of the pulp and the recycled papers. In the meantime, the use of biomass-based materials such as nanocellulose and multifunctional materials such as cationic poly diallyldimethylammonium chloride (p-DADMAC) is growing and attracting attention from various technical and environmental aspects. Therefore, in order to improve the properties of the product and the production process, the effect of nanocellulose and p-DADMAC as polymers with the aforementioned potential was studied on a laboratory scale.Material and Methodology: Recycled brown pulp was prepared from an OCC domestic mill without any additives and with a Canadian standard freeness (CSF) of 350 ml. Medium molecular weight cationic polydiallyldimethylammonium chloride (poly DADMAC) from Sigma Aldrich and cellulose nanofibers with an average diameter of 35 nm from Nano Novin Polymer Co. were purchased. The addition of chemicals to the pulp slurry was studied at four levels: 0, 0.1, 0.15, and 0.2 based on oven dry (O.D) mass of pulp. Effects of the polymer additions, individually and in combination, on pulp properties including CSF, total retention, and material loss in the DDJ analyzer, as well as on the properties of laboratory handsheets including density, tensile, bursting, and tearing strength indices, were investigated according to TAPPI standards procedures. Results: The individual addition of cationic p-DADMAC (patching system) resulted in an increment of total retention of the recycled pulp ingredients, but increasing the amount of addition did not significantly change the total retention. It also reduced the amount of material loss through passing the DDJ screen and increased the pulp CSF from 350 ml in the control sample without any additives to 430 ml at the lowest level of p-DADMAC usage (0.1%). It also significantly improved the apparent density, but higher levels of p-DADMAC did not have a significant effect on this structural property of the recycled paper. Regarding the tensile and bursting strengths of the recycled paper, the single application of p-DADMAC and increasing its dosage caused some changes, mainly increasing but relatively limited. Cellulose nanofibers, when used alone, also resulted in an increase in the total retention and density, tensile and bursting indices of the paper; and a decrease in tear index, CSF, and material loss from the pulp in the DDJ analyzer. The anionic nature, high specific surface area, and hydrogen bonding potential were reported to be the reasons for such results. The use of cellulose nanofibers after p-DADMAC to the pulp as a complex system in the wet end of papermaking has increased the total retention of the pulp ingredients on the wire of the laboratory handsheet maker, which can be reported in the form of reduced material loss. It also often has a significant and severe adverse effect on CSF and has made drainage slower and longer. The use of nanocellulose after p-DADMAC has also had different effects, mainly increasing, on the tensile, bursting, and tearing resistance of the produced recycled packaging paper, depending on the percentage of each of the additives. Conclusion: It was shown that, except for the undesirable reducing effect of the single application of nanocellulose on the tear index and CSF freeness, in other single and complex addition treatments of chemical additives of nanocellulose and poly-DADMAC, an increase in all strength properties and paper density, improvement of drainage ease of recycled pulp, increase in pulp retention during paper formation, and reduction of material loss can be achieved compared to the control treatment. However, the single application of the cationic polymer showed better results in pulp in terms of retention and drainage than the single application of nanocellulose and their combination. The trend of changes in strength properties also depended on the percentages of combined application of two different chemicals.
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