IRANIAN JOURNAL OF WOOD AND PAPER INDUSTRIES
Year:2020 | Volume:11 | Issue:2|Papers Count:13

In this study, the utilization of fibers recycled from MDF wastes and waste papers for manufacturing fiberboards was investigated. The proportion of waste paper to recycled fibers from MDF wastes was 70/30 and 50/50. Also the effect of utilization of poly vinyl acetate adhesive on properties of boards was investigated. Boards were manufactured at density of 0. 3 g/cm3 and dimension of 30×30×1. 2cm. Practical properties of boards including thickness swelling, bending strength, modulus of elasticity and internal bonding were measured. The results showed that the utilization of adhesive can improve all of board properties. Change in proportion of recycled fibers to waste paper had different influences on various properties of manufactured fiberboards. The proportion of 70/30 of waste paper to recycled fibers from MDF wastes led to improving bending strength and modulus of elasticity of fiberboards, while the manufactured boards from proportion of 50/50 had better results about thickness swelling and internal bonding. Overall, it can be concluded that recycled fibers from MDF wastes mixed with waste paper can successfully utilize in producing fiberboards.

For investigation on the effect of densification on the physical and mechanical properties of the chemically and thermally modified poplar wood (Populus deltoides), thermal modification at 170° C, chemical modification with glutaraldehyde, and compression at three levels of 10, 25, and 40% at the hot pressing time of 2h were carried out. With increasing compression ratio from 25 to 40%, the density of thermally and chemically modified samples increased by 13% and 8%, respectively. Spring back and moisture absorption of the thermally modified/compressed samples was more than chemically modified/compressed ones. Water absorption and thickness swelling for 10% compression ratio were more than the chemical and thermal control samples but significantly decreased with increasing compression ratio. The mechanical properties of both thermally and chemically modified samples were improved with increasing compression ratio. From 25 to 40% compression, improvement of bending modulus for both modified samples were more than 10 to 25%, which was more significant for the thermally modified samples. Bending strength was also improved with increasing compression ratio, but the intensity of improvement decreased by 40% compression. Increasing of compression ratio also led to a significant improvement of the compression strength parallel to grain and hardness, which was more obvious for glutaraldehyde modified specimens than the thermally modified ones.

Wood is one of the most important natural resources and its preservation is unavoidable for increasing the service life of wooden products. Wood modification with hot oil causes a steady transfer of heat into the wood and reduce its hydrophilicity through a chemical change of wood macromolecules. This study investigated the effect of oil heat treatment with linseed oil on the chemical structure and physical properties of wingnut wood. Specimens were heated at 140, 170, and 200 Cº for 2 and 4 hours. Results showed that water absorption of modified samples were lower than the control ones, and subsequently water absorption and thickness swelling of the modified samples decreased with increasing temperature. However, the time of modification had no significant effect. Also, Fourier-transform infrared (FTIR) analysis confirmed the reduction of hydroxyl groups in the modified samples, which this reduction was more sensible with increasing the temperature of modification.

This research was carried out with the aim of bleaching of soda-bagasse pulp, produced in the Pars paper industry, with oxygen (O), chlorine dioxide (D), and hydrogen peroxide (P) in the presence of titanium dioxide nanoparticle (T) as photo catalyzer and methylene blue (M) as an alternative to sodium hypochlorite (H). Bleaching of pulp was performed in sequences of O, OD, OD (Ep) T1, OD (Ep) T2, OD (EP) T1m and OD (Ep) T2m. The physical and mechanical properties of pulp and handsheets were measured as well as COD of effluents. According to the results, the kappa number of the pulp was reduced in two treatments of OD (EP) T1m, and OD (Ep) T2m and was the same as the control sample, bleached with HH conventional sequence in the Pars paper industry. However, the degree of polymerization of the two recent treatments was twice more than that of the control sample. The results of degree of brightness showed that the OD (Ep) T1, OD (Ep) T2, OD (EP) T1m, and OD (Ep) T2m sequences can result in the same degree as the bleached control sample of the Pars paper industry (75% ISO). Also, results showed that by replacing the HH sequence with OD (Ep) T1m and OD (Ep) T2m sequences with the same kappa number, an improvement in bleached pulp yield (3%), viscosity (207%), degree of polymerization (213%) of pulp, opacity (5%), tensile strength index (2. 7%) and tear index (49%) of the paper can be expected, while the COD of effluent would decrease by 30%. In general, the use of titanium dioxide nanoparticles and aqueous methylene blue in OD (Ep) bleaching sequence can result in the higher pulp brightness and strength properties of paper.

The production operation plays a crucial role in reducing the environmental impacts in various stages of the life cycle of products, from the extraction of materials to production, end-use, reuse, and recycling. Therefore, the process of reducing these environmental impacts in relation to production contributes to achieving competitive advantages and increased market shares. As such, discursive approaches to prevent industries from acting as pollutants are proposed. Since the medium density fiberboard industry is among the industries which consume high volumes of materials and energy, this study is considered to be a strategic model for enhancing efficiency and minimizing pollution and energy consumption within the framework of continuous improvement of the protection of the environment. To this aim, through the AHP, a three-level hierarchy, five criteria (product modification, process change, bill of material implementation, recycling, and human resources), and 45 sub-criteria were analyzed at Kimia Choob Medium Density Fiberboard Industry. The overall results showed that process change, among the main criteria, and planning to prevent unnecessary stoppage in machinery and equipment used as a sub-criterion were identified as the highest priorities. The total inconsistency ratio is 0. 1, which proves the consistency of the results.

The objective of this study was to investigate the physical and mechanical properties of glulam made from compressed poplar wood (Populus deltoides) by technique of Combined Hygro-Thermo-Mechanical Treatment (CHTMT) which is combination of two techniques of hygrothermal treatment and densification of wood. The poplar wood blocks were initially treated hygrothermally at temperatures of 130, 150, and 170° C for holding times of 20 and 40 minutes. Afterwards, the densification process was carried out under a hot press (at 160° C for 20 minutes) at two levels of compression set, i. e. 40 and 60 percent based on the blocks thickness (radial direction). For production of glulam, the blocks were jointed together by finger joint and polyurethane resin. The produced glulam were physically and mechanically tested for its water absorption, radial and tangential swelling, delamination, bending strength, modulus of elasticity and shear strength. Results revealed that physical and mechanical properties of glulam were enhanced due to the CHTMT treatment. According to the results, water absorption and radial swelling of glulam were increased due to the CHTMT, significantly. Moreover, this treatment reduced the delamination of samples after soaking-drying cycles. It was also found that the CHTMT could significantly enhance mechanical properties of glulam such as bending strength and bending modulus of the elasticity; but decreases shear strength of glue line. Generally, results showed positive effects of CHTMT in glulam production.

Crude oil is a toxic product for biological systems and is an important contaminant in the marine environment. So far, many methods have been used to clean up oil pollution in the seas, one of which is purification by a variety of adsorbents. In this study, wood lignocellulosic sorbents of poplar species in three forms of sawdust, straw, and wood chips and fibers in three forms of chemical, mechanical and recycled pulp were investigated for the cleanup of oil contamination from the water surface. Also, the effect of adsorbent weight, temperature, and crude oil concentration, each in three levels, were other variables in this study. The results of the studies showed that the absorption rate of crude by the six different adsorbents with different weights and temperatures had a significant difference. Also, the results showed that among the adsorbents, mechanical pulp having the absorption rate of 90. 5% and wood chips having the absorption rate of 39% had the highest and the lowest amount of purification of crude oil from aqueous media.

At present, public awareness and participation in waste separation from the source have not been applicable much due to the management rules and lack of familiarity with the urban affairs of the city administration. Therefore, the purpose of this study was to investigate the level of public awareness and participation in waste separation in Behbahan city. For this purpose, a descriptive and analytical research method was used by the field method. The statistical population of the study was the citizens of Behbahan city in 2019 among whom a sample of 384 people was selected by simple random sampling and a questionnaire was distributed. The results showed that 50. 5% of the population had a moderate level of knowledge regarding waste separation. Based on the level of awareness of the subject, people are aware of: the need to separate waste from the source for a sustainable society, to have adequate information for waste storage, to protect the environment by reducing waste generation, and to reduce environmental pollution by reducing waste generation, respectively. However, they were poorly aware of the usefulness of separating waste from the source for the community and having space for the waste generated with the economic benefits of waste collection. The findings also showed that 58. 8% of the people are low in terms of participation. Based on the extent of popular participation by the subject; based on the use of waste separation training programs by source, separation of recyclable waste components from source and avoidance of spillage of waste on the street, motivation, and purpose in separating waste from source, respectively were good partnerships. But they were poorly involved in planning to reduce waste production and participate in training programs.

The purpose of this study was to investigate the factors affecting the economic growth of the classical furniture industry and to present a model of the impact status and effectiveness of the Air Conditioning Index. Soon after interviewing wood industry professors, experts, and certified furniture manufacturers, Delphi techniques, production management indicators, Product quality, human factors, design, marketing, and economics were identified. Using the DEMATEL technique, the degree of impact-effectiveness of each of the indicators was determined and the model was presented accordingly. The results showed that the marketing and economics index (9. 736) had the highest impact on other indices and in order to improve economic and marketing status, it is necessary to address firstly human factors (1. 45) and then to design and quality of furniture (0. 0204). Also, production management (19. 080), which is at the top of the production process of a product, has the most interaction with other indicators.

Nowadays, new and environmentally-friendly methods of wood preservation have been focused. One of these methods is the bio-protection of wood against destructive agents in which microorganisms are used to protect the wood instead of chemicals. The aim of this study was to protect the beech and spruce wood against white and brown rot using a bacterium extracted from beech (Bacillus amyloliquefacien). For this purpose, B. amyloliquefaciens was first placed in a dual culture medium against wood-destroying fungi and then in wood specimens. The results showed that this bacterium inhibited the growth of destructive fungi in both media. The studied bacterium is capable of producing chitinase, amylase, and cellulase enzymes and the microscopic study confirmed the results of weight loss tests. Overall, here, for the first time, B. amyloliquefaciens is proposed as an efficient bio-control of wood decay.

In this study, we investigated the biometrical properties of fibers, the physical and microscopic properties of Morus alba wood. For this purpose, three healthy mulberry trees were randomly selected and cut in Babol city (Mazandaran province). Three discs of 5 cm thickness were prepared at breast height, 3 m height, and 4. 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 examined. Then the biometric properties of fibers including fiber length, fiber lumen diameter, fiber diameter, and cell wall thickness were measured. Also, microscopic sections of wood close to the pith and bark were studied using light microscopy according to the List of International Association of Wood Anatomists (IAWA). Anatomy of the wood near the pith and bark of the Morus alba tree revealed differences. Vessel grouping and its arrangements near the pith were more radially, while these features were more clustered near the bark. Rays in the area of the pith were more heterogeneous, while near the bark, many rays were homogeneous. The mean tangential vessel diameter near the larger bark (237 microns) was greater than that of the near-pith wood (144 microns). The porosity of wood was observed to be ring porous, near the bark, and semi ring porous near the pith. The results also showed that there was a significant difference in both the transverse and longitudinal directions of the Morus alba tree in terms of length, fiber diameter, fiber lumen diameter, and the cell wall thickness. The biometric properties of the fibers increased from the pith to the bark. The mean length, total diameter, fiber lumen diameter and cell wall thickness of the fibers were 1. 51 mm, 27. 25 µ m, 18. 74 µ m, and 8. 5 µ m, respectively.

The purpose of this research was the investigation of sanding sequence and coating thickness effect on adhesion strength of coating in two species: beech and elm. For this purpose, beech and elm veneers with 0. 6 mm thickness were laminated on MDF with 16 mm thickness by UF and hot press. The surface of the laminated panels was sanded by two different sequences; the soft (180-280 grits) and rough (150-180 grits) one. Before the coating application, the surface was sanded with 400 grits. Then they were coated with polyurethane in two forms of one and two-layered coating. After that, the adhesion strength test was done on specimens according to ASTM D4541. To have a more precise investigation of the interphase region of coating-veneer, photomicrographs were captured by fluorescent microscopy to analyze and calculate the effective penetration parameter of the coating into the wood texture. The results showed that two species respond to sanding sequences differently and a thicker coating layer increased the adhesion strength. Beech as a diffuse-porous wood had the finer texture and higher density compared with elm. Therefore, the adhesion strength of the beech veneer was declined by 13. 8 % and reaches 2. 59 MPa due to the use of a rough sanding sequence. However, these sequences caused the opposite result in elm veneer and led to a 25. 7 % adhesion improvement (3. 23 MPa). The study on microphotographs and the effective penetration parameter stated that an even thickness of the coating layer and effective penetration reduction has been possible when the rough sequence and soft one are applied on elm and beech, respectively.

One application of hydrogels is to use them as dressings (wounds and burns). Biocompatibility and cytotoxicity are of particular significance for hydrogels used in the medical field. Cellulosic materials can load and relief drugs at temperatures or pH levels of the body as a result of contrary processes such as diffusion. The aim of this study was to investigate the mechanism of release of silver nitrate in nano-cellulose-based biodegradable hydrogel film for burn repair. To prepare a hydrogel in the form of film, cellulose nanofibers and hydroxyethyl cellulose were used with the weight ratio (3: 1), and also, the citric acid was used as a crosslinker in different amounts of 10 and 20 wt% matrix. Later on, the loading silver nitrate as a disinfectant drug into selected hydrogels was performed. Drug release results illustrated that there was a direct relationship between absorption rate and drug concentration. In the initial times of the testing, 70 to 90% of the drug release was detected and then for 24 h, the drug was gradually released from the hydrogel. Investigation of modeling drug-releasing selected kinetic diffusion as the dominant mechanism in drug delivery. MTT non-toxicity test displayed high efficacy of nanocellulose cationization and confirmed the non-toxicity of biocompatible hydrogels. It can be concluded that biodegradable nanocellulose based hydrogel containing silver nitrate can be used as an appropriate and relevant product for burn repair.