Research Paper
Physics and Mechanical Wood
Majid Kiaei
Abstract
Background and Objective: Physical, biometric, and mechanical properties of wood are important indicators for assessing the quality and potential industrial and ecological applications of different wood species. Juniperus excelsa, due to its slow growth and unique cellular structure, exhibits distinctive ...
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Background and Objective: Physical, biometric, and mechanical properties of wood are important indicators for assessing the quality and potential industrial and ecological applications of different wood species. Juniperus excelsa, due to its slow growth and unique cellular structure, exhibits distinctive characteristics in terms of density and mechanical strength. However, limited information is available regarding the variation of these properties along radial and longitudinal axes of the tree stem. This study aimed to investigate and analyze the changes in physical, biometric, and mechanical properties of J. excelsa wood along radial and longitudinal axes, and to identify patterns of variation from pith to bark and from the base to the top of the stem.
Materials and Methods: Three healthy J. excelsa trees were selected in the Hezar Masjed Mountains (Darghaz, Iran), and three stem sections were collected from each tree at breast height (1.3 m), 3 and 6m height. From each stem section, three radial samples from pith to bark were prepared for measuring physical properties (air-dried density, basic density, and volumetric shrinkage), biometric properties (tracheid length, tracheid diameter, and cell wall thickness), and mechanical properties (bending strength and modulus of elasticity). Data were analyzed using two-way ANOVA to examine the effects of radial and longitudinal positions on wood properties.
Results: The mean air-dried density and basic density, and volumetric shrinkage were 0.442 and 0.413 g/cm³, and volumetric swelling was 10.80%, respectively. Tracheid length, tracheid diameter, and cell wall thickness were 1.572 mm, 31.41 µm, and 5.58 µm, respectively, while bending strength and modulus of elasticity were 41.66 MPa and 4.47 GPa. The study demonstrates that physical, biometric, and mechanical properties of J. excelsa wood are strongly influenced by the sampling position along radial and longitudinal axes, with identifiable patterns from pith to bark and from the base to the top of the tree.
Conclusion: These findings provide valuable information for industrial applications of J. excelsa wood and sustainable management of its forest resources.
Research Paper
Management and Economics wood
Mohammad Reza Fathi; Kazem Teymouri
Abstract
Background and Objective: The transition to a circular economy and the expansion of closed-loop supply chains have made recycled paper a strategic raw material source in the paper industry. However, in reverse logistics and recycling chains, the quality of recycled materials is inherently uncertain, ...
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Background and Objective: The transition to a circular economy and the expansion of closed-loop supply chains have made recycled paper a strategic raw material source in the paper industry. However, in reverse logistics and recycling chains, the quality of recycled materials is inherently uncertain, which affects production process stability, operational decisions, downtime and scrap costs, and market acceptance. In Iran as well, despite the economic and environmental inevitability of paper recycling, institutional and operational challenges have caused the quality of recycled inputs to remain variable and negotiable in many cases. Accordingly, this study aims to explain how “quality governance” is formed in Iran’s recycled paper supply chain, which boundary judgments and institutional assumptions reproduce the current quality situation, and, based on this understanding, what defensible reform implications and actionable recommendations can be proposed.
Materials and Methods: This research adopted a qualitative approach, and its analytical framework is based on Critical Systems Heuristics and its twelve boundary questions. The logic of Critical Systems Heuristics relies on a systematic comparison between the current state and the desired state, making it possible to render explicit and open to critique the boundary judgments related to objectives, decision-making authority, valid knowledge, and the legitimacy of decisions. Data were collected through semi-structured interviews with 20 experts and key actors in the recycled paper supply chain. Participants were purposively selected from the main links of the chain and included managers and specialists from factories that use recycled paper (especially those responsible for procurement, production, and quality control), collection/sorting and processing actors, intermediaries and wholesalers, and individuals familiar with standards, testing, and oversight mechanisms. The experts’ professional activities were located in the country’s main hubs connected to the recycling network and the paper industry, and interviews were conducted to capture diverse perspectives in Tehran and Karaj, Isfahan, the northern provinces, and Khuzestan. After transcription, interview texts were coded using the twelve boundary questions and reorganized across four dimensions—motivation, control, knowledge, and legitimacy; then, to increase transparency and traceability, the results were translated into institutional axes and corresponding reform packages.
Findings: The results showed that in the current state, the dominant goal of quality governance is largely focused on maintaining the flow of supply and transactions and ensuring short-term feedstock provision, while success criteria are defined mainly in economic and operational terms; therefore, quality is often reduced to the minimum level required for acceptance or continued production. In the control dimension, decision-making regarding acceptance/rejection, grading, and pricing is dispersed and multi-centered and, alongside some formal rules, remains significantly reliant on market conventions and case-by-case agreements. In addition, asymmetry in access to levers such as volume aggregation, market information, the ability to mix loads, access to large customers, and testing tools and results turns quality into a negotiable variable and reproduces quality fluctuations. In the knowledge dimension, although field experience plays a central role, the lack of integrated and reliable data and the absence of uniform procedures for sampling, testing, and producing defensible reports cause quality decisions and disputes to rely on informal information, limiting evidence-based dispute resolution. In the legitimacy dimension, weaknesses were observed in representation and accountability channels regarding quality claims and decisions; affected and cost-bearing groups do not necessarily have an effective ability to influence rules or follow up decisions, and as a result, the dominant logic tends toward a market-centered, transactional view.
Conclusion: This study indicates that single-link or purely technical interventions are insufficient for sustainable quality improvement, and that reforming quality governance must simultaneously strengthen shared rules, reliable data, aligned incentives, and accountability. Based on the findings, four proposed executive reform packages are presented: (1) “standards and testing infrastructure” to turn quality into a measurable and defensible criterion through minimum indicators, uniform sampling/testing, and periodic audits; (2) “transparency and data governance” to reduce information asymmetry through a load quality sheet, record-keeping, and standardized access to documentation; (3) “quality-based contracts and incentive alignment” through quality-dependent pricing and reward/penalty mechanisms for nonconformance; and (4) “regulation, accountability, and dispute resolution” through clarified responsibilities and test-based arbitration. The gradual and coordinated implementation of these packages can enhance input quality stability, reduce the costs of poor quality, and improve supply reliability across the chain.
Research Paper
Composite wood products
Mohammad javad Hassani; Mosayeb Dalvand; Meysam Mehdinia; Hamid Zare hosseinabadi
Abstract
Background and objectives: The furniture industry, as one of the strategic sectors in the value chain of wood products, faces challenges such as increasing functional quality, reducing structural weight, increasing durability and reducing environmental impacts. The use of advanced materials and engineered ...
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Background and objectives: The furniture industry, as one of the strategic sectors in the value chain of wood products, faces challenges such as increasing functional quality, reducing structural weight, increasing durability and reducing environmental impacts. The use of advanced materials and engineered structures can provide an effective solution to respond to these challenges. Glass fiber reinforced Polymer (GFRP) sandwich panels are considered a promising option for furniture applications due to their high strength-to-weight ratio and ability to improve mechanical performance. The aim of this research is to investigate the manufacturing process and evaluate the technical performance of glass fiber reinforced sandwich panels and to assess the feasibility of their application in the panel furniture industry.Methodology: For this purpose, the effect of parameters including the type of glass fibers, dosage fiber, type of resin used (two-component polyester and epoxy), and the arrangement of reinforcing layers (symmetrical and asymmetric) on the mechanical properties of the panels was investigated. The panels were produced with a honeycomb paper core and the reinforcing layers were attached to the surfaces using a lamination process.The samples were subjected to standard ASTM mechanical tests including bulk density, modulus of rupture, modulus of elasticity, edge pressure resistance, surface pressure resistance and shear strength.Results: The results showed that reinforcing sandwich panels with glass fibers significantly improved mechanical properties, especially flexural strength, modulus of elasticity and compressive and shear strengths. Also, the symmetrical arrangement of the reinforcing layers showed better structural performance than the asymmetrical arrangement due to a more uniform distribution of stresses.Conclusion: In summary, glass fiber reinforced sandwich panels using epoxy resin, especially in symmetrical arrangements are a suitable option for application in lightweight and durable panel furniture structures. In addition to improving mechanical performance, this approach can be effective in achieving sustainable development goals and optimizing resource consumption in the furniture industry by reducing raw material consumption and structural weight.
Research Paper
Composite wood products
َAlireza Mirhasanniasarabi; Morteza Nazerian; Sima Sepahvand; Sepideh Hamedi
Abstract
Background and Objectives: Corner joints are among the most critical components of wooden structures and products, playing a decisive role in load transfer, structural stability, and durability. The mechanical performance of these joints is influenced by several factors, including joint type, board thickness, ...
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Background and Objectives: Corner joints are among the most critical components of wooden structures and products, playing a decisive role in load transfer, structural stability, and durability. The mechanical performance of these joints is influenced by several factors, including joint type, board thickness, wood species, and bonding quality. An inappropriate selection of joint type or board thickness may result in stress concentration, reduced strength, excessive deformation, and premature structural failure. Despite the widespread use of traditional and engineered wood joints in the wood and furniture industries, comprehensive experimental information regarding the combined effects of joint type and board thickness on the ultimate load of corner joints, particularly in fir wood, is limited. Therefore, the present study aimed to investigate the effects of joint type and board thickness on the ultimate load on fir wood corner joints in order to identify the most suitable combination in terms of mechanical performance and provide guidance for improving the design and safety of wooden structures.
Materials and Methods: Fir wood was used as the raw material in this study. Five joint types, namely butt joint, mortise-and-tenon joint, dowel joint, half-lap joint, and dovetail joint, were evaluated. Wooden boards were prepared at six thickness levels (1.0, 1.5, 2.0, 2.5, 3.0, and 4.0 cm), and the joints were fabricated from these boards using polyvinyl acetate (PVAc) adhesive. Three replicates were considered for each combination of joint type and thickness. A total of 90 specimens were prepared. After the adhesive curing period, the specimens were subjected to shear testing, and the failure load of each specimen was recorded as the ultimate load indicator. The experimental data were analyzed using SPSS software through two-way analysis of variance (ANOVA) to evaluate the individual effects of joint type and board thickness, as well as their interaction on the ultimate load of the corner joints. Statistical significance was ascertained at P < 0.05.
Results: The statistical analysis indicated that the developed model exhibited a satisfactory fit and that the investigated variables accounted for a substantial proportion of the variation in ultimate load. The effects of board thickness, joint type, and their interaction on the ultimate load of the corner joints were all statistically significant (P < 0.05). The results demonstrated that the butt, mortise-and-tenon, dowel, half-lap, and dovetail joints exhibited significantly different mechanical behaviors and ultimate load values. Furthermore, increasing board thickness generally enhanced the ultimate load of the joints; however, the magnitude of this improvement varied depending on the joint type. These findings indicate that joint type and board thickness jointly determine the load-bearing capacity and ultimate load of wooden corner joints and should not be considered independently in joint design.
Conclusion: The results demonstrated that the ultimate load of fir wood corner joints was significantly affected by joint type, board thickness, and the interaction between these two factors. Significant differences in mechanical performance were observed among the butt, mortise-and-tenon, dowel, half-lap, and dovetail joints. Increasing board thickness generally improved the ultimate load of the joints, although the extent of improvement depended on the joint configuration. Therefore, the selection of an appropriate joint type should always be made in accordance with the board thickness to maximize load-bearing capacity, structural strength, and durability. The findings of this study provide useful guidance for the selection and design of wood joints in the wood products, furniture, and timber construction industries and may contribute to the optimization of their mechanical performance.
Research Paper
Composite wood products
Javad Torkaman
Abstract
Background and Objective: Particleboard is a wood composite material that can be produced using various lignocellulosic materials. Therefore, lignocellulosic wastes play an important role in this regard. One of the agricultural wastes that is available in large quantities in the north of Iran is rice ...
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Background and Objective: Particleboard is a wood composite material that can be produced using various lignocellulosic materials. Therefore, lignocellulosic wastes play an important role in this regard. One of the agricultural wastes that is available in large quantities in the north of Iran is rice husk. It can be used in the production of particleboard. The lifespan and durability of particleboard depend on the quality of raw materials, binders, manufacturing conditions, and how it is used. As a result, achieving the durability of mechanical properties and dimensional stability of these boards is importance in the applications of indoor and outdoor exposure. Therefore, the aim of this study is to investigate the effect of isocyanate resin on the physical and mechanical properties retention of the rice husk particleboard.
Materials and Methods: The samples in this study were prepared from rice husk particles which has been stored in the laboratory for eighteen years after manufacture. These boards were made from natural rice husk particles with a slenderness ratio of 60, a flatness ratio of 10, and an aspect ratio of 6 as the raw material, and 10 percent of urea-formaldehyde resin which was partially replaced with isocyanate resin at three levels of 0, 1, and 2 percent as a binder. Three pressing temperatures of 170 and 180 degrees Celsius and three pressing times of 5 and 6 minutes. A total of 36 experimental boards were made with three replicates for each treatment. Test samples were prepared from each board according to EN326-1 guidelines. The measured properties included water absorption and thickness swelling at 2 and 24 hours, Modulus of Rupture, Internal Bonding, and their percentage of retention. For statistical analysis of the data, a completely randomized block design at a confidence level of 95% was used, and for comparison of means, the Tukey test was used in SPSS software.
Findings: The results of this study showed that isocyanate resin affected all physical and mechanical properties of the boards. The use of 2% isocyanate resin has caused a 100% increase in mechanical properties and a 50% decrease in physical properties. Retention percentages for water absorption and thickness swelling in the 2% isocyanate treatment were obtained 92% and 98%, respectively. In other words, the water absorption and thickness swelling of the boards increased 8 and 2% respectively between 2008 and 2025.The percentage of the modulus of rupture and internal bonding retention of boards made with 2% replacement of urea formaldehyde with isocyanate after 18 years has been 35 and 25%, respectively.
Conclusion: In general, the best result can be observed in samples produced with 10% resin (2% isocyanate plus 8% urea-formaldehyde) at a pressing temperature of 180°C and a pressing time of 6 minutes. In these samples, the highest retention percentages were for water absorption and thickness swelling.
Research Paper
Pulp and paper
Omid Darvishzadeh; Ahmad Jahan Latibari; Amir Lashgari; Shadman Pourmousa; Ajang Tajdini
Abstract
Background and Objectives: Pulp refining is considered as an essential unit operation in the development of the paper properties. However, it is intensive energy consumer in the era that world is struggling with energy shortage. Therefore, paper industry has been searching various alternative including ...
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Background and Objectives: Pulp refining is considered as an essential unit operation in the development of the paper properties. However, it is intensive energy consumer in the era that world is struggling with energy shortage. Therefore, paper industry has been searching various alternative including application of chemicals to reduce refining energy. Also, during the refining stage, compressive and shear stresses cause swelling, flexibility, and internal and external fibrillation of the fibers, increasing the potential contact surface for fiber bonds. On the other hand, excessive refining can increase fiber shortening and fines production. The objective and aim of this research were concentrated on the application of cellulase enzyme as an environmentalfriendly process to optimize the refining energy and improve the properties of pulp fibers and paper.Material and Methods: Two sequences of enzyme treatment and refining were used; first enzyme treatment then refining called ER and first refining then enzyme treatment call RE. Pulp mixture was composed of 70% hardwood kraft and 30% softwood kraft pulps. Three dosages of enzyme were selected at 200, 300, and 400 ppm (based on dry weight of pulp) and three reaction times of 60, 90, and 120 minutes. Sample preparation and all tests were performed according to TAPPI standard test procedures. The freeness of the pulp of each of the 19 treatments (control and 18 treatments) was measured, hand sheet was prepared, and strengths and optical measurements were performed. The analyses included response surface models selected on the basis of leave-one-out cross-validation. Principal component analysis (PCA), hierarchical clustering, descriptive comparison of nine condition-matched pairs, rank correlation, and multi-response desirability analysis coupled with sensitivity analysis.Finding: Based on the average values of the results, the values of ER treated pulps compared to RE were varied as follow; burst strength index, 2.5 against 1.70 kPa.m2/g, tensile strength index, 51.43 against 42.16 N.m/g and brightness 82.88% against 80.05%. However, tear strength index was lower after enzyme treatment. The highest values burst strength index and tensile strength index values obtained applying ER300-120 treatment were 2.90 kPa.m2/g, and 60.14 N.m/g respectively. Principal component analysis (PCA) was performed on 14 complete, non-constant response variables after z-score standardization. Hierarchical clustering was conducted using Ward’s method and Euclidean distance. Given the nature of the available data, the statistical comparisons and conclusions were reported on a descriptive and exploratory basis.Conclusions: The results of strength properties, freeness degree, and optical properties showed that the order of enzymatic treatment and refining is effective on pulp performance. The average values of the measured properties for ER treatment were higher than respective values for RE treatment. The values of burst strength index and tensile strength index were 66.7% and 43.5% respectively higher than control sample. The response of the RE treatment was not uniform and the average values of the tensile strength index was fairly higher than control sample, but the other properties were lower than control. The tear strength index of all treatments was lower than control which can be attributed to destruction of the fiber integrity. This finding necessitates the appropriate selection of variables to reach optimum results.
