مجله صنایع چوب و کاغذ ایران
سال سیزدهم شماره 4 (زمستان 1401)

In this study, bending creep behavior of poplar (Populus alba) plywood made by thermoplastic films was evaluated. For this purpose, the poplar wood layers (2.2 mm thickness) were prepared and the plywood samples were made using high density polyethylene (HDPE) film, polypropylene (PP) film, the mixed high-density polyethylene-polypropylene (PP/HDPE) films and, urea formaldehyde (UF) glue, as a binder, in 5 replications. The maleic anhydride grafted high-density polyethylene (MAPE) was used as a coupling agent. The three-point bending test was performed, and the maximum failure load, modulus of elasticity (MOE) and modulus of rupture (MOR) were measured according to EN-310. Then 20% of the maximum failure load of the samples was determined. To measure the creep parameter, the four-point bending creep test was performed based on 60 minutes of loading time (going) and 30 minutes of unloading time (returning). The results indicated that the plywood made of urea formaldehyde glue and also mixed polypropylene-polyethylene film had highest MOE and MOR and the samples made of polyethylene film had the lowest values of MOE and MOR. The results of the creep test indicated that the highest value of the creep modulus and the lowest value of relative creep were observed in the plywood made with urea formaldehyde glue. The boards made with polyethylene film showed the highest relative creep due to the decrease in modulus of elasticity and bending strength. The use of polypropylene film and the mixed high-density polyethylene- polypropylene (PP/HDPE), both showed an increase in the creep modulus due to the stiffness of polypropylene. The coupling agent caused a better transfer of stress and showed an increase in creep modulus and a decrease in relative creep by improving the level of sharing between the base material and the film.

Staining with fluorescent materials is one of the widely used methods in studying and locating cellulosic materials. In this study, the staining of cellulosic materials was investigated by two approaches as direct (direct addition of fluorescent labelling agent) and indirect (adding fluorescent label after creating an anchor) methods; then the staining results were compared. The results showed that although imaging was possible in both methods, indirect staining provided relatively more uniform and effective image results during this investigation. The results showed although fluorescent imaging was possible following both methods, the use of indirect staining method provided relatively better and cleaner image results during this investigation. Moreover, the effect of each staining method on the surface charge property (zeta potential of nanofibers) and wet-end interactions (via freeness testing as an indicator) were studied. The results showed that the (negative) zeta potential of cellulose material became more negative as a result of staining following both staining methods. It was also observed that the staining of the cellulose material by both methods did not affect the freeness as an indicator.

In this research, the effect of chemical treatment of palm particles with alkoxysilan on the mechanical and physical properties of wood-cement particleboard was investigated. For this purpose, palm particles were chemically treated with 7.5% and 15% alkoxysilane to make wood cement particleboard with a weight ratio of 30 to 70 and in the presence of 5% calcium chloride (based on the dry weight of cement). Test samples of mechanical (bending strength and modulus of elasticity and internal bonding) and physical (water absorption and thickness swelling) were prepared in three levels of control, 7.5% and 15% alkoxysilane according to the European standard. The results showed that the chemical treatment of palm particles with alkoxysilane had a positive effect on the mechanical and physical properties of wood cement particleboards, so that with the increase of alkoxysilane up to 15%, the maximum mechanical resistance and the lowest physical properties were obtained. The significant increase in the resistance and physical properties of the boards resulting from the addition of 15% alkoxy silane can be attributed to the reaction between the hydroxyl groups of the palm constituents with the active groups of alkoxysilane and greater cohesion between the palm particles and cement. In order to describe the effectiveness of chemical treatment, discriminate analyzes such as infrared spectroscopy and scanning electron microscopy were used. The results of Fourier transform infrared show an increase in the intensity of the peaks related to Si-O bonds in the samples modified with alkoxysilane and as a result of the chemical modification of palm particles. Also, the uniform and coherent structure of the scanning electron microscope of wood cement particleboard modified with silane agent has indicated the chemical reaction between palm particles, alkoxysilane and cement, and as a result, more compatibility and entanglement between modified palm particles and cement.

The present study aimed at producing bio-based superabsorbents with minimum use of polymeric materials and crosslinkers. Thus, nano-zeolites were used as high potential minerals for development of an environmentally friendly, durable, accessible, absorbent and cost-effective organic nano-hybrid composite in low amounts of crosslinkers and polymeric materials as an alternative for synthetic hydrogels. In the experimental stages, the modified heat-treated carboxymethyl cellulose (CMC) powder developed in the previous research as well as the unmodified powder (control sample) were individually dispersed in distilled water and then a 3:1 ratio of nano-zeolite and hydroxyethyl cellulose together with citric acid as a crosslinker were added. The solution was then cast in a petri dish. The prepared samples were then measured and evaluated using centrifuge, absorption under load, deformation and swelling time tests. The results showed that the combination of nano-zeolite with heat-treated CMC increased absorption capacity both free and under load, fine toughness and higher absorption rate of hydrogel. In addition, thermal modification successfully decreased the need for crosslinking so that nanocomposite hydrogels had considerable mechanical hardness. Besides, this combination of hydrogels demonstrated the highest amount of absorption in centrifuge and AUL tests with the most desirable results in the swelling time. Also, the addition of nano-zeolite increased the water absorption in samples in the absence of hydroxyethyl cellulose, however, in presence of hydroxyethyl cellulose, two properties of absorption rate and toughness showed higher values.

This research aimed to investigate the mechanical performance, thermal stability, and viscoelasticity of reinforced rapeseed flour/ high-density polyethylene composites with different amounts of nanographene. Rapeseed flour and high-density polyethylene with equal weight ratio, along with compatibilizer (3 phc) and nanographene at four levels of 0, 0.5, 1, 1.5, and 2 phc were used to make the samples. The viscoelastic and thermal behavior of the samples were evaluated by dynamic-mechanical thermal analysis (DMTA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Also, the dispersion distribution of graphene nanoparticles in composites was studied by a field emission scanning electron microscope (FE-SEM). The results showed that the addition of nanographene to the composites increased the storage and loss modulus and improved the thermal stability of the composites by increasing the thermal oxidation degradation temperature and residual carbon. The results showed that the addition of nanographene to the composites increased the storage and loss modulus and improved the thermal stability of the composite via increasing the thermal oxidation degradation temperature and residual char. The microscopic images showed that the use of nanographene improved the adhesion between filler and polymer.

In this study, pulp nanocrystals (PNCs) and pulp nanofibrils (PNFs) were extracted from bleached soda pulp with D0EpD1 sequence, and their characteristics were compared with lignocellulosic nanocrystals (LCNCs) and lignocellulosic nanofibrils (LCNFs) obtained from unbleached soda pulp. LCNCs were extracted with an acid hydrolysis method using sulfuric acid (64 wt%) at 45◦C for 45 minutes with a liquor to fiber ratio of 17.5: 1 and LCNFs were produced via microfluidizer by passing through three chambers with diameters of 50, 100, and 200 μm for 2, 4, and 6 hours, respectively. SEM and AFM images confirmed the needle-like and spherical-like structure of lignocellulosic nanocrystals and the stringy structure of lignocellulosic nanofibrils. XRD results showed that D0EpD1 bleaching increased the crystallinity of nanolignocelluloses. The results obtained from TGA thermal calorimetry analysis show that D0EpD1 bleaching increases the thermal stability of the produced PNCs and decreases the thermal stability of the produced PNFs. FTIR results confirmed that the amount of hemicelluloses and lignin was reduced from the fiber surface after D0EpD1 bleaching sequence

Brand gender refers to personality traits related to masculinity and femininity, which includes two independent and universal dimensions: male brand personality traits and female brand personality traits. In this research, the effect of brand gender on loyalty with the mediating role of brand love and understanding of brand quality in Pak Choub Industrial Group was investigated. The statistical population is the customers of Pak Choub Industrial Group, which due to the unknown number, the statistical sample was selected using the Morgan table of 384 people and using the available non-probability sampling method. The questionnaire of Carvalho et al. (2020) was used to measure the variables. Data analysis was done using Amos software and structural equation modeling method. The results showed that brand gender has a positive and significant effect on brand love, perceived quality and loyalty. Also, cooperation has a positive and significant effect on brand love and perceived quality, and brand love and perceived quality also mediated the relationship between brand gender and brand loyalty

In this report, fiber biometry and microscopic features of pomegranate wood were discussed. For this purpose, pomegranate trees were selected and cut from the gardens of Neka city (Mazandaran province). Three discs of 5 cm thickness were prepared at breast height, 2.5 m height, and 3.5 m height. In the transverse direction, the test specimens were cut 2 × 2 cm to 3 cm from the pith to the bark sequentially and were examined. Fiber biometric properties including fiber length, fiber lumen diameter, fiber diameter and cell wall thickness were measured. Also, the anatomical properties of pomegranate wood were studied according to the IAWA list of microscopic features for hardwood identification using a light microscope. Wood anatomical features of pomegranate are as follows: diffuse-porous with multiple vessel groupings in the radial direction (in most cases), homogenous rays, simple perforation plates, alternate intervessel pits, the average length of vessel elements shorter than 350 microns. The results of fiber biometrics showed that there is a significant difference in the length of fibers, the diameter of fibers, the diameter of fiber lumina, and the thickness of the cell wall of the fibers, both in the radial, and in the longitudinal direction of the pomegranate tree stem. So that the biometric properties of the fibers increased from the pith to the bark. The average fiber length, fiber lumen diameter, fiber diameter and cell wall thickness of the fibers were measured as 0.75 mm, 22.5 µm, 18.3 µm and 4.2 µm, respectively.

Cross-Laminated-Timbers (CLT) absorb/desorb moisture from surrounding atmosphere when exposed to wet/dry conditions; such all engineering massive wood-based products. The moisture gradient occurs due to this process, which is responsible for moisture induced stresses. In the current research work, the moisture induced stresses due to the moisture gradient have been studied in the CLT. The sample panels were made with 5-plys. One and two plys of hydrothermally treated wood at 150°C were placed on both sides as surface layers. Afterwards, the sample panels were exposed to wet to dry cycles (RH of 88 to 32%) and dry to wet cycles (RH of 32 to 88%). Results revealed that the moisture gradient as well as the moisture induced stresses are reduced due to application of the hydrothermally treated laminations on both side of the panels in comparison with control samples.

The purpose of this research is to investigate the possibility of producing hybrid particleboard from industrial wood chips with waste from vine pruning as a waste material that has no specific use and is thrown away. For this purpose, the particles from grapevine pruning residue and industrial wood chips were mixed with different ratios of 0:100, 30:70 and 40:60. Also, for making boards, two different levels of urea-formaldehyde resin were used, including 10 and 12% (based on the dry weight of wood chips) and the pressing time was 5 minutes. The physical and mechanical properties of the boards including thickness swelling (TS), bending strength (MOR), modulus of elasticity (MOE) and internal bonding (IB) were measured and then all the data were analyzed statistically. The results of this research showed that although the increase of particles from grapevine pruning waste led to a decrease in the characteristics of particleboards, but all the boards meet the European standard. On the other hand, increasing the resin content moderates the negative effect of these particles on the characteristics of the board and had a positive effect on all the characteristics of the boards. Therefore, by comparing the properties of the boards produced with the European standard (EN), it was determined that by using 30% of grapevine pruning wastes replaced with wood chips, it is possible to produce particleboard with desirable properties. The general results of this study show a positive result in the direction of using the wastes from pruning grape trees as a type of garden waste that is rejected after pruning and can also replace part of wood material in the construction of industrial panels and also it will be an income for gardeners.

Since the information related to heat treatment of wood by industrial method is mainly related to coniferous wood, this research seeks to investigate the physical and mechanical properties of birch wood after heat treatment in the industrial furnace. For this purpose, birch wood according to the instructions of the Thermowood Association of Finland for the production of Class D Thermowood was used. Water absorption, dry and critical density and 12% Moisture, shrinkage, swelling, and color components (L*a*b*), anatomical features and wettability test, mechanical properties of wooden samples including MOE, MOR, impact strength and compression strength parallel to gain were evaluated and compared to the control samples. The results showed that the color of thermos-treated wood has become significantly darker than the control one. In birch wood, the moisture content of heat-treated wood showed a decrease of 117.7% compared with the control sample. The critical density of heat-treated wood showed an increase of 7.3% compared with the control sample. The dry density of the sample after heat treatment showed a decrease of 0.6% compared with the control sample. The density after heat treatment showed an increase of 2.3% compared with the control sample. The shrinkage and swelling of the thermos-treated sample showed a decrease of 100.5% and 115.4%, respectively, compared with the control sample. It was more difficult to prepare the section of the heat-treated wood than the control sample, while destruction of vessels, fibers, and rays was visible. The modulus of elasticity, modulus of rupture, impact strength and compression strength parallel to gain of the heat-treated samples showed a decrease of 3.22, 3.4, 147.97 and 2.95%, respectively, compared with the control sample.