Iranian Journal of Wood and Paper Science Research
Year:2016 | Volume:31 | Issue:3 (56) |Papers Count:14

Chips washing pre-treatment are an important factor in chemi-mechanical (CMP) pulping. Therefore, this research was conducted to investigate the effect of Populous deltoids wood chips washing pre-treatment on CMP optical (brightness and opacity) and strength (tensile and burst indecies) properties. Pre-treatment was accomplished with pure hot water and alkaline solution (NaOH) at three levels of concentration (0. 5, 2 and 3. 5 percent). Pre-treated and control (without washing) chips were pulped by CMP process. The results of indicated that the pretreatment with hot water and also alkaline solution reduced the wood chips mass but increased the pulp yield and brightness. Pulp strength was reduced and refining energy consumption increased. Chip pretreatment dissolved part of chip hemicelluloses which imparted some negative effects on pulp refinability and pulp strength reduction.

In this research the effect of moisture content and cutting speed on the specific cutting energy and shearing stress for four varietiesof almond tree (Mamayy, Rabi, Sefid and Shahrodi12) wood was investigated. Shear properties of almond wood was measured using a universal testing machine (Santam STM20). One side beveled knife with the edge angle of 40 degree was used. Three moisture levels of 18, 25 and 45% (wet basis) wet basis, three cutting speeds 20, 30 and 40 mm/min and three stem diameter of 6, 9 and 12 mm were selected. The results of analysis of variance (ANOVA) showed that the effect specific cutting energy and shearing stress were significant (P<0. 01). The results showed that both specific cutting energy and shearing stress increased at higher moisture content. However, increasing cutting speed from 20 to 40 mm per minute reduced these values. Based on the results of the study, the average specific cutting energy were determined for varieties Mamayy, Rabi, Sefid and Shahrodi12 as 59. 41, 56. 088, 54. 38 and 77. 57 J/ mm2 respectively and shearing stress as 16. 01, 14. 34, 13. 73 and 19. 35 MPa, respectively. Also, according to shear test results, it can be expressed that the moisture content and the variety of almond tree are most effective and the effect cutting speed is relatively low.

In this study, the effect of using different percentages of Layer-by-Layer (LbL) treated pulp mixed with refined OCC recycled pulp on paper physical properties was investigated. The LbL treatments were conducted to build 7 consecutive cationic and anionic starch layers. OCC pulp was refined for 10, 15 and 20 minutes. The LbL pulp was mixed with either refined OCC pulp at three levels of 10, 20 and 30 percent. Hand sheets with basis weight of 60 g/m2 were prepared using different mixtures and the physical properties including: thickness, density, roughness and formation were examined. The results of LbL treatment using AFM micrographs indicated that the surface of fibers was covered with starch polymer particles. Also, SEM micrographs confirmed that surface of the fibers covered with starch is rough. Analysis of interactive effect of independent variables revealed that addition of LbL-treated pulp to the refined recycled pulp had only significant effect on paper thickness and surface roughness, while variation of refining time had significant influence on all physical properties. Considering the results of ANOVA test, the interactive effect of the content of LbL-treated pulp and different refining times on the paper physical properties using response surface method, it can be expressed that adding 10 % of LbL-treated pulp to the OCC pulp and applying the refining time of about 18. 66 minutes can be considered as the optimum condition.

In this study, changes in optical behavior of poplar kraft lignin before and after methylation by dimethyl sulphate was determined by measuring optical indices (brightness, K, S, K/S and post-color numbers) of impregnated papers following accelerated photo aging. The structural changes in lignin caused by methylation reaction were verified using FT-IR spectroscopy. The results showed that, by methylation of lignin in methylated lignin-containing papers, the extent and stability of brightness is higher and PC number is lower compared to control samples. In methylated samples, the phenomenon of photo bleaching was observed. Therefore, it can be expressed that, methylation of lignin can prevent the formation of quinone groups and increases the stability of the optical indices in the photo aging conditions.

In this study, the effect of nano-wollastonite addition on strength and fire resistance characteristics of wood flour/polypropylene composite was investigated. The composites samples were manufactured using a dry blend/hot press method. In this study, beech dried wood flour was used as the filler for poly propylene as the matrix. Composite sample were prepared using 60% polypropylene, 37% wood flour and 3% polypropylene grafted with maleic anhydride as the coupling agent. Nano-wollastonite was used in four levels ( 0, 1, 3 and 5% based on dried wood flour). Nominal density and dimensions of the composites were one g/cm3 and 1*20*25 cm, respectively. Bending strength was measured according to ASTM standard test methods and fire resistance characteristics including flammability, duration of flame and glow after removing the burner, and mass reduction were measured according to ISO 11925. Results indicated that by increasing the nano-wollastonite the bending strength, MOE and flammability increased but mass reduction, duration of flame and glow decreased. The dispersion of nano-wollastonite in composites was evaluated by Filed Emission Scanning Electron Microscopy (FE-SEM).

The aim of this study was to investigate the effect of furfurylation on glueline shear strength and screw withdrawal resistance of beech (Fagus orientalis) and fir (Abiesalba) woods. Specimens with two different degrees of furfurylation i. e. low (fir 14% and beech 20%) and high (fir 38% and beech 65%) were prepared and evaluated in comparison with untreated specimens. The furfurylation was performed after by impregnating the specimens by furfuryl alcohol under vacuum condition followed by heating to complete polymerization and crosslinking. Test specimens were prepared according to ASTM D 905 to assess shear strength of glueline formed with three different types of adhesives, single-component polyurethane, polyvinyl acetate and urea-formaldehyde. Also screw withdrawal resistance of wood polymer specimens was measured perpendicular to grain and parallel to grain. The results indicated that the shear strength of the glueline decreased and screw withdrawal resistance increased by furfurylation level. Examination of adhesion mechanism demonstrated that formation of an appropriate interface between water-soluble adhesives and wood-polymer involves effective penetration of adhesive into cell wall. Hence, the interface of adhesives and material would be the determining factor in developing strength of adhesive joints. Since the wood-furfuryl alcohol polymer is formed in cell-wall, the possibility of creating an appropriate interface by increasing of furfurylation level was impaired. On the other hand, the adhesion mechanism of polyurethane glue compared to water-soluble adhesives such as polyvinyl acetate and ureaformaldehyde is significantly different. The screw withdrawal resistance of furfurylated wood was increased by furfurylation level due to changing the nature of wood and increased shear strength of wood-polymer. This was also more evident in fir than beech wood. The results showed that screw withdrawal resistance perpendicular to grain was higher than parallel to grain.

The oil-impregnated dielectric papers are the main components of distribution transformer which govern its service time. Therefore, durability enhancement of this grade of paper will cause to extend transformers life. In this research, long fiber unbleached Kraft pulp and its mixture with bagasse soda pulp at the ratios of 20% to 80% were used to make oil-impregnated dielectric papers with the grammage of 60 g/m2. The effect of dicyandiamide impregnation and its content in the paper structure and thermal aging were then assessed on dielectric properties and tensile strength of the insulation papers. The results showed that with increasing dicyandiamide content, the capacitance and tensile strength index decreased in comparison with untreated samples, but dielectric loss, insulation resistance, and breakdown voltage were improved. However, slight changes were observed in most dielectric properties during aging, but dicyandiamide caused to prevent loss of the tensile strength of insulated papers. Generally it could be concluded that dicyandiamide acts efficiently in thermal stabilization of insulation paper exposed to aggressive conditions inside the oil-filled transformer.

This research was conducted to determine the optimum condition for modification poplar wood with 3-(trimethoxysilyl) propyl methacrylate and its effect on the physical properties of the wood. Test samples were divided into five groups: control, acidified ethanol/Silan at two subgroups of 110 and 150˚ C, and Ethanol/Silan/150° C at two subgroups of with and without Benzoyl peroxide. Samples were impregnated with silan compound using vacuum-pressure method in an experimental cylinder. Highest weight gain (24/40%) were determined at Silan/Et/BP/150˚ C. Silan/AEt/150˚ C specimens which showed most bulking efficiency and OH group's substitution 6. 81% and 1. 10 mol/gr, respectively. Modification reduced the water absorption and caused in dimensional stability improvement, and maximum dimensional stability were determined in samples modified using initiator containing solutions. After the immersion-drying cyclic test, the highest and lowest bulking efficiency were reported for Silan/AEt/150˚ C and Silan/Et/150˚ C. Maximum weight loss in immersion-drying test was determined in Silan/AEt/150 by the amount of 94/6%.

In this research, the performance of a semi-greenhouse solar kiln was evaluated for dying different wood species in different season in Karaj. This study was carried out in two separate parts. In the first part, the flat-sawn boards of oak and fir wood with a nominal thickness of 50 mm were dried during summer of the year 2012. In the second part, the flat-sawn boards of beech and poplar wood with the same thickness were dried in autumn, 2014 and spring, 2015. For both parts, the boards were also air-dried. The temperature measured inside the solar kiln was 35 º C greater than that outside during daytime and the kiln temperature ranged from 55 to 75º C during 10 a. m. to 2 p. m. In both parts of research, all wood species dried in the solar kiln faster with better quality compared to those air-dried. The severity of casehardening and surface checking in the boards dried in the solar kiln was lower and more homogenous moisture profile was observed. In addition, the final moisture content was lower for the boards dried in the solar kiln.

The aim of this study was the evaluation the Nano-silica and wood flour calcareous-treated and the properties of the wood plastic Nano composite obtained from these compounds. For this propose, wood flour was treated by calcium hydroxide and then combining with weight ratio of 60 to 40phc polypropylene and 4 per hundred compound (phc) MAPP was melt extruded. In addition nano silica at weight ratio of 0, 1, 3 and 5 phc was used. Wood plastic nano composites were fabricated by injection molding technique. Fourier transform infrared spectroscopy was used to determine the wood flour changes after chemical treatment and for morphological study of nano composites, scanning electron microscopy and X-ray diffraction were used. Mechanical testes including bending (ASTM D790) and tensile (ASTM D638) and physical testes including water absorption and thickness swelling (ASTM D7031-11) on the samples were done. Results showed that by calcium hydroxide treatment, bending and tensile resistance were decreased but bending and tensile modulus were increased. Also with increasing the Nano silica up to specific range, the mechanical properties were improved. Increasing the Nano silica in untreated samples caused increasing of water absorption and in treated samples caused decreasing of water absorption. With increasing of Nano silica, thickness swelling in the samples was decreased. The results of infrared spectroscopy showed that after lime treatment No change has occurred in the absorption band related to the hydroxyl groups. Results of scanning electron microscopy showed that the needle-shaped crystals of calcium hydroxide formed calcium silicate crystals after addition the Nano silica. As well as results of X-ray diffraction, confirmed calcium silicate crystals.

The aim of this research was to use a natural component, renewable and environmentally friendly material (silk cocoon) as reinforcing component for urea formaldehyde resin in the plywood manufacturing and investigate its influence on physical and mechanical properties of plywood. For this purpose, silk cocoon was used as filler and reinforcement at four levels of 0, 10, 20 and 30 percent (based on dry weight of urea formaldehyde resin). The physical and mechanical properties of samples including water absorption and thickness swelling after 2 and 24 hours immersion in water, bending strength parallel and perpendicular to the surface layer grain and shear strength were measured. The results show that increasing the content amount of silk cocoon decreased water absorption and thickness swelling after 2 and 24 hours immersion in water and increased bending strength parallel and perpendicular to the surface layer grain and shear strength. So that, using 30 percent of silk cocoon improved dimensional stability, bending strength and shear strength.

The objective of this study was the determination of the best method of bleaching including refining and bleaching (RB) or bleaching and then refining (BR) on chemical mechanical pulp (CMP) for the production of newsprint. Wood raw material consisting of mixed forest species wood was chipped and air dried to to equilibirium moisture content. Wood composition for CMP pulping was 40% poplar, 30% maple, 7. 5% oak, 7. 5% alder, 7. 5% willow, and 7. 5% Persimmon. In order to remove heavy metal ions from pulp, the chelating was carried out with DTPA. TCF Bleaching was carried out by 3% H2O2 and 2. 5% NaOH based on dry weight of pulp with initial brightness of 44. 6% ISO. Pulp bleaching was done in two stages, before and after the refining by laboratory PFI mill beater. Finally, handsheets were made from the RB and BR treated pulps and the sheet properties were evaluated according to TAPPI test methods. The results showed that BR treatment increased tensile, burst, tear indices, brightness, scattering coefficient, and density, but reduced yellowing, opacity, and light absorption coefficient.

In this study, the effect of "aligning marketing strategy" on "supply chain performance" and "organizational performance" in office furniture companies was taken into account. The study population was firms where based in the industrial towns aroundTehran, such as Chahardangeh, Khavaran and Parand. At last, 206 samples were collected. This is, based on purpose, of applied research. However, it is a descriptive survey in terms of data collection. For analyzing of hypotheses and research questions, "structural equation modeling"was used. According to the results, the impact of aligning marketing strategies on the value of supply chain in office furniture firms was determined as 7. 45 at 95% confidence level and also the effect of the value of supply chain on organizational performance was gained at 4. 19 at the same confidence level. Both indicated the relationships in hypotheses were significant. It was concluded that aligning marketing strategies had improved organizational performance directly and increased the value of supply chain indirectly in active companies in the office furniture industry which helped to improve "organizational performance. "