مجله تحقیقات علوم چوب و کاغذ ایران
سال بیست و نهم شماره 1 (پیاپی 46، بهار 1393)

The influence of fiber lignin content and the dosage of coupling agent on the strength and physical properties of cellulosic fiber-polypropylene composite were investigated. The old corrugated container (OCC) fibers were delignified using sodium hydroxide to reach the lignin content of 2. 7، 3. 78، 5. 26 and 7%. Fibers were compounded with polypropylene by extrusion process using 20% fibers and 77% PP and the extrudate was cooled and grinded to fine granulates before injection molding. MAPP coupling agent was applied at three different levels (1، 2 and 3 percent based on the total weight of the composite). The strength properties of the composites were measured using relevant ASTM test methods and the results were statistically analyzed using factorial experiment under complete randomized design. The impact of fiber lignin content of flexural strength of composite was statistically significant at 98 percent significance level and the lowest and highest values of flexural strength of composite were measured at 3. 78 percent and 7 percent lignin content of fiber. The interactive effect of fiber lignin and MAPP on the tensile strength and flexural modulus of elasticity of the composite showed that at lower values of lignin and higher dosage of MAPP، these properties are 38. 7 and 3438 MPa respectively. Other strength values of the composites were also improved and at lower content of lignin and increaing dosages of the MAPP، the impact strength of the composites was increased from 52. 82 J/m to 60. 26 J/m.

In present competitive world، packaging has a significant effect on the rate of sale. Unfortunately، in Iran''s packaging industry، the variation of printing methods is too low which leads to reduction in quality of packing and the amount of sale. Therefore، some manufactures prefer to send out their products to be packed. In this paper، to achieve an acceptable quality in printing the paper packaging، four factors of paper roughness، ink viscosity، grindometer (unresolved droplets of ink particles) ink and paper thickness were studied. Fractional factorial designs are used to evaluate the factors. Each factor is investigated in two levels. Based on obtained results، all the factors have a significant impact on response.

The objective of the present study was the utilization of rose flower residues for the production of medium density fiberboard. MDF was produced applying two moisture gradients of 0 and 4% between surface and core layer، two press temperatures of 175 and 185 °C and three pressing times of 3،4 and 5 minutes. The mechanical and physical properties of the boards were measured and statistically analyzed using factorial experiment and complete randomized design. In case statistical difference was observed between the averages، then Duncn multiple range test was used for grouping of the averages. The results revealed that the moisture gradient statistically influenced the flexural strength and internal bonding of the boards. In both moisture gradients، the internal bond of the boards increased and the maximum was reached when 5 minutes pressing time was applied. The pressing time also statistically influenced the thickness swelling and the lowest values were measured on boards pressed for five minutes. Generally، the strength properties of the boards were in accordance with the required specification of EN standard، which indicates that rose flower residue can be considered as a suitable raw material for medium density fiberboard production.

Cereal straws including grain sorghum varieties can be used for pulp production due to the significant amount of residual straw after harvesting. This study showed that there are no significant differences between fiber dimension and papermaking coefficients of two varieties of sorghum (Kimia and Sepideh). The average of fiber length، fiber width، lumen diameter، and cell wall thickness were measured as 1. 19 mm، 23. 20، 15. 34، and 3. 93 µm، respectively. Significant difference (P < 0. 05) was found among all chemical composition of two varieties except lignin content. The average content of holocellulose، alpha-cellulose، lignin، extractive، and ash were determined as 62. 13%، 37. 71%، 21. 05%، 9. 58% and 6. 97%، respectively. The result revealed that pulp strength produced from Sepideh variety was better. However it requires more intense delignification compared to Kimia variety. The highest screen yield (33. 19%) was reached applying the treatment combination of 170°C، 12% NaOH، and 75 minutes from the Sepideh variety. Sorghum pulp could be combined with the virgin pulp to compensate cellulose raw material shortage in paper industry.

Imported lumber of Norway spruce called European spruce (Picea abies L.) from Russia have a variety of applications. However، the presence of fungal agents in this wood، their application is limited. In addition، some the fungi associated with these woods are able to cause disease in human. In order to identify the presence of such fungi in the imported woods from Russia، samples were collected from Asalem region. Isolation and preparation of pure colonies of fungi grown on woods was done using ascosporic or conidial mass suspensions and single spore method. The morphological characteristics of fungi grown on wood pieces and on culture media were studied using light microscope. The results showed that Ophiostoma piceae in sexual phase and Sporothrix sp. and Graphium spp. in asexual phase are present in these woods. In the culture، Ophiostoma sp. with asexual stage of Sporothrix sp. and Ceratocystis sp. with asexual stage of Chalara spp. was identified. The results of microscopic examination of woods in cross and radial sections showed that fungal hypha penetrated the resin canals، the ray parenchyma، tracheids، and cross-field areas

Tobacco (Nicotianan tabacum) and an old industrial plant in the north، Iran to supply tobacco leaf to produce significant amounts of stem tobacco cultivation and the annual production is in the north of the country. In this research stems of tobacco variety Coker 347 randomly Gilan district، city of Astara was prepared according to the TAPPI standard test، wood flour were prepared and extractives were determined. The results showed that the mean shoot extractive tobacco varieties Coker 347 (10. 41 percent). The extractive solvent toluene - ethanol volume ratio (2:1) of milled wood was extracted. Extractive made into a glass vial and transferred to the BSTFA reagent was added. Samples for one hour at room temperature and 70 ° C water bath and then by (GC / MS) were analyzed. Atotal of 11 chemical compounds in tobacco stem wood extractives variety Coker 347 were identified with different percentages of tobacco stem wood Coker 347 varieties exist. These compounds include، P- Prydyn، 1 – tri methyl Saylyl، 1،2 - benzene di- carboxyl acid، alpha - D - Golokopyranoz، 11، 8 – di methyl - 13 - (4 - aksu -1 - methyl)، tri Floyver methyl isopropyl sulfide are the highest values.

Member joints and furniture designs are very important in the production of these elements and the strength of the structure is affected by both the joints and designs. The performance of the chairs made from poplar wood against the front to back load test and also، mechanical strength of mortise and tenon and dowel joints were evaluated and compared. Two types common wooden chairs having side stretcher or without side stretcher، and also the chairs structured by common joints and poly vinyl acetate (PVA) adhesive are evaluated and their maximum strength were measured. The results showed that treatments and intercept treatments were statistically significant with the 95% confidence. Duncan analysis for comparison of the averages showed that maximum load of different treatments can be classified into four category; A; Pattern of side stretcher with mortise and tenon joint (984. 5 N)، B; Pattern of side stretcher with dowel joint (892. 4 N)، C; Pattern without side stretcher with mortise and tenon joint (303. 3 N)، D; Pattern without side stretcher with dowel joint (260. 2 N). Since، all treatments showed statistically significant differences، it can be conclude that the maximum strength of the chairs is significantly influenced by the pattern of side stretcher and the other factor is the mortise and tenon joint.

This study lignin from unbleached hardwoods chemimechanical pulp was extracted and the chromophor functional groups of the lignin were studied. Acetylation and reduction treatments were perfomed and samples were analyzed by FT-IR spectroscopy. A mild acidic dioxin extraction method was employed to isolate lignin. For the acetylation and reduction treatments of lignin acetic acid and sodium borohydride were used respectively. The results of untreated and treated (acetylated and reduced) lignin spectra showed that، the major of lignin chromophor groups such as hydroxyl and carbonyl groups have been reduced or eliminated by these treatments. In the acetylated lignin، the absorption band of hydroxyl groups has been weakened and in the 1743. 16 Cm-1 region، acetoxy compounds band has appeared and also a cluster absorption band was observed in the 1228. 76 Cm-1 region. In the reduced lignin، most of the absorption bands of the carbonyl groups have been weakened or eliminated، especially in the 1705. 56 and 1629. 54 Cm-1 region.

The objectives of research were to create tree ring chronology of juniper trees and investigation on the relationship between the growth rate of the tree and the climate. Juniper trees are naturally distributed in High Mountain with semi-arid and arctic climate condition of Iran. Samples were collected from 20 trees in Shah-Kouh Mountain with 54° 42´ 58˝ longitude and 36° 61´ 01˝ latitude coordinate. Increment core were prepared and analyzed. The time span for tree ring chronology was 271 year (1741-2012 AD). Tree ring chronology statistic for MS، EPS، SNR، were 5. 6، 0. 85، 0. 29 respectively. Correlation between tree ring index and climate data showed that mean temperature in the previous growing season is an important factor for growth of juniper trees. The result of this research can help the development of climate data and is useful for the creation of weather atlas.

The objectives of research were to create tree ring chronology of juniper trees and investigation on the relationship between the growth rate of the tree and the climate. Juniper trees are naturally distributed in High Mountain with semi-arid and arctic climate condition of Iran. Samples were collected from 20 trees in Shah-Kouh Mountain with 54° 42´ 58˝ longitude and 36° 61´ 01˝ latitude coordinate. Increment core were prepared and analyzed. The time span for tree ring chronology was 271 year (1741-2012 AD). Tree ring chronology statistic for MS، EPS، SNR، were 5. 6، 0. 85، 0. 29 respectively. Correlation between tree ring index and climate data showed that mean temperature in the previous growing season is an important factor for growth of juniper trees. The result of this research can help the development of climate data and is useful for the creation of weather atlas.

In this paper، we attempted to investigate the relationship between consumption، demand for imports of fine paper and economic growth using annual time series data in the period of 1984 to 2010. Since the time series are non-stationary (Unit root) and can lead to spurious regression، the stationary of the variables are investigated in its logarithmic form using Augmented Dickey Fuller test (ADF) in two type of intercept without trend and intercept with trend. After applying the unit root test، in order to understand the interaction between economic growth and consumption and imports of fine papers and direction the causal relation، the vector auto regressive (VAR) approach including two models and the causality test of granger are used. The results indicate that GDP growth will increase the consumption of writing and printing papers but this relation is one-sided. On the other hand، there is no causality between changes in GDP and imports of printing and writing paper، and vice versa. Also، there is the one-side causality between GDP and consumption of newsprint. In the case ofThe Granger causality between economic growth and imports of newsprint، due to reject the null hypothesis، there was no relationship found، and vice versa

In this study، some anatomical، chemical and physical properties of toothbrush wood (Salvadora persica L.) of Zabol region in Sistan and Baluchestan province were investigated. Anatomical studies showed that thi s species has short vessel with intermediate diameter، simple perforation plate and alternative intervessel pits. Ray parenchyma is homogeneous and of the procumbent cell type. Axial parenchyma is storied as seen in the tangential section and resembles paratracheal confluent arrangement in the cross section. Included phloem was present in xylem. The average fiber length، total diameter، lumen diameter and fiber wall thickening were 1898. 5، 19. 4، 8. 2 and 5. 6 µm، respectively. Chemical characteristics also showed that، toothbrush wood has average cellulose، lignin، extractives and ash content about 33. 5، 21. 5، 6. 8 and 7. 5%، respectively. The results also showed that the specific gravity of the wood was 0. 49 and its mean tangential، radial and longitudinal shrinkages were 7. 4، 7. 8 and 0. 98 %، respectively.

In this study، effects of the flour of cellulosic shell of Pistachio and nanoclay loading on the physical and mechanical properties of wood plastic composite were investigated. Hence، flour of cellulosic shell of Pistachio، in levels of 30، 40 and 50 and Nano clay of cloisite 15A in three levels (0، 3 and 5%) was mixed with Corn starch polymer. Samples were made with a laboratory twin-screw extruder and then injection molding. The heating temperature profile and rotational speed of the screws were set at 180–170–160–160 oC and 60 rpm، respectively. Mechanical properties including tensile and flexural properties as well as notched impact strength and physical properties including water absorption and thickness swelling were measured. The results showed that flexural and tensile strength، water absorption of the samples increased as the flour content increased from 30 to 50% (w/w)، but tensile modulus، notched impact resistance and thickness swelling decreased. Furthermore، tensile modulus increased as the Nannoclay content increased from 0 to 5% (w/w). Besides، Flexural and tensile strength، Flexural modulus، notched impact resistance increased as Nannoclay content increased from 0 to 3% (w/w). beyond this limit (to 5% (w/w))، they decreased. Water absorption and thickness swelling of the samples decreased as the Nannoclay content increased from 0 to 5% (w/w).

Due to the nature of wood and paper companies and the risks and incidents in which there is، the importance of safety and safety culture is essential for working in these industries. The aim of present study was to investigate the knowledge and attitudes of employees regarding safety culture. In this cross-sectional study، 236 workers were examined and the data confirmed the reliability and validity of the questionnaire were collected. The data using appropriate statistical tests were analyzed by spss software. A total of 236 persons، 64% wrere high school graduated and less than، 8% were Technicians and 18% were BA and MA. Mean years of age and experience، respectively were 19. 55، 7. 02، 43. 65، 7. 40، sd، respectively. The results showed that eight important factors has the most important role for contributing of the safety culture. After the factors rotation on each other، the variance accounted for over 45% of the variance that the three first factors، management commitment، the level of information exchange، directing to the rules and Instructions are 11. 41، 9. 6 and 5. 05 respectively. Eight factors influence on improving the safety function and proper development of safety function in the studied companies. Managers with appropriate training programs، work safety and safety of staff will play an important role in the culture and knowledge of safety.

In this study، rice straw as an abundant and cheap raw material selected to produce soda - anthraquinone pulp. Nano fiber Cellulose of rice straw were added to improve the pulp strength after cationing. Cationed suspension was mixed at three levels including 2، 5 and 10 percent with nano fiber cellulose. Starch and polyacrylamide as cationic chemicals were used to stabilize nano fiber cellulose at 1. 5% and 0. 2% based on oven dried pulp، respectively. The result showed that there is linear change between stock drainage time and paper strength according to nano fiber cellulose added content. Tensile and burst index were improved at 18. 66% and 18. 12% respectively by adding 10% of nano fiber cellulose to suspension treated with cationic polyacrylamide. Furthermore، the two indices increased until 19. 35% and 19. 24% by adding of maximum amount of nano fiber cellulose (10%) to cationed pulp suspension with cationic starch، respectively. The use of nano fiber cellulose had a positive significant effect on paper properties.