Iranian Journal of Wood and Paper Science Research
Year:2008 | Volume:22 | Issue:2 (27)|Papers Count:10

In this study the pulping of bagasse using TMAH and EDA as organic bases was investigated and compared to conventional Soda and Soda-AQ bagasse pulping. Resulting pulps properties including Kappa number, reject, screen yield of pulp and optical and mechanical properties of handsheets prepared from them were determined and compared. Kappa number of TMAH pulp was considerably lower than others. Also, optical properties of TMAH and TMAH-NaOH pulps were considerably higher than Soda and Soda-AQ reference pulps. As well as, addition of EDA to pulping liquor resulted suitable pulp with better properties compared to Soda pulp. Based on the obtained results, it was concluded that the delignificatiom mechanism of TMAH differ to hydroxide ion from NaOH and probably it improves the delignification rate through increasing of lignin degradation and its solubility.

Wood Plastic Composite as new wood component products is made by wood fiber or powder elements with thermoset or thermoplastic materials. In recent periods of ten years the components have been produced by west industrial countries and as well in United State of America as wood water resistant materials. Samples of wood plastic and untreated wood specimens of maple and elm were prepared in laboratory. The effects of water, fire and fungus (Trametes versicolor) on the wood samples with using ASTM and EN standards were investigated. The results showed that the highest resistance wood samples against fire was related to wood plastic made by polypropylene and the lowest resistance of wood samples was associated to untreated maple. In the case of floating samples in water, results indicated that increase cross section of wood plastic decreases the rate of water penetration in wood samples. The results of fungal attack in laboratory tests on wood plastic samples showed that component made by 30% polypropylene and 30% polyethylene and 40% wood fiber is able to resist significantly against rotting fugal.The weight loss of untreated maple samples against fungal attack was 38.5% that probably is related to being high percent of sugar and starch materials in wood species. There was a difference about 3% of weight loss between natural maple (control) and maple treated by sea water. Therefore, maple is a perishable species in wood durability classification. Heartwood of elm was very resistant to wood rotting fungus and the mean weight loss of wood samples was 3.75%. As a result in wood classification this wood specie is very durable. Appling of sea water only 0.5% increased wood resistance to fungal activity. The results of fungus attack on wood plastic showed this wood product is very resistant and during 6 weeks incubation only 3.14% of its weight was decreased.

This research was carried out to study the influence of acetylation on paper dimensional stability. Specimens from printing paper and Texon paperboard were oven dried and then treated with acetic anhydride at 120°c for 30 and 60 min without catalyst. Acetylated papers were soaked in water for 2 and 24 h. afterwards, bulking effect of the acetylation and thicknesses swelling of the specimens as well as anti-swelling-effect (ASE) were determined in the treated specimens.Results revealed that the bulking of the specimens were increased by reaction time. However, in case of Texon, it was slowed down after 30 min of the reaction time. The thickness swelling of the treated specimens was significantly reduced after soaking in water for 2 and 24 h compared with untreated samples. As it was expected the acetylation increased ASE in Texon and the printing papers.

In this study flexural properties Wood-plastic composites (WPCs), the composites made from high density polyethylene(virgin, recycled and mix of them) and four types lignocellulosic fillers (wood sawdust, sanding of MDF, particleboard sawdust and rice hull) at %60 by weight fiber loadings were manufactured using a dry blend/hot press method. Nominal density and dimensions of the panels were 1g/cm3 and 35x35x1cm, respectively. After conditioning, flexural properties of the panels including flexural modulus and flexural strength were determined. The results show the flexural modulus and strength wood plastic composites containing sanding MDF and particleboard sawdust were higher than those made from other fillers. The flexural modulus and strength were affected by kind of high density polyethylene (virgin or recycled).

The present study deals with effects of CMP  fines on Mechanical Strength of newsprint papers ,for which, different batches for CMP fines (0%,10%.20%.30%) of totally 80% is taken. where the remaining 20% of imported long fiber pulp was taken as fixed amount.The study focused on analyzing the effects of CMP fines on Mechanical Strength of newsprint paper, after mixing the pulps and making the handsheets.Generally, the results show the 20% increase in CMP fine amount lead to increase, Folding Endurance and Tensile Strength and decrease in Tear Strength and Tensile Stiffness, Also that changes in CMP fines has no effect on Burst Strength.

Wood consumption is increasing in different regions of the world and population growth is also enforces this demand. Since the world natural forests are limited, therefore, different societies has concentrated their effort on fast growth plantation species especially various poplar species and clones. Iran has also concentrated on importing and cultivating different poplar species. Among them two clones (P.deltoids 77/51 and P.deltoides 69/55) showed both excellent adaptation and growth in Gilan. Therefore, wood producing farmers paid special attention on these clones. Even thought both adaptation and growth is favorable for plantation of these clones, but their wood technological characteristics must fulfill the industrial requirement. Since fiber geometry of any wood will influence its application for industrial commodities, therefore, in this study, the fiber geometry of these clones including fiber length, diameter, lumen diameter and cell wall thickness were measured. Fiber length, diameter and cell wall thickness of P.deltoids 77/51 were measured at 947, 25.35 and 5.24 micron respectively. The related values for P.deltoids 69/55 were at 971, 24.99 and 5.46 micron respectively

In this study the effects of resin content and press time of particleboard from prosopis (Mesquite) wood were investigated .Variable factors were resin content (9, 10 and 11 percent) and press time (5, 6 and 7 minutes) . Other factors such as type of resin (UF), hardener content (2 percent) type of hardener (NH4Cl) press closing time (4.5 mm/sec.), board density (0.7gr/cm3), press pressure (30 kg/cm2) and press temperature (160C) were considered as constant parameters. In total 27 boards were manufactured in laboratory. Physical and mechanical properties of boards were tested according to EN standards. This study was designed based on factorial and data was analyzed using ANOVA techniques. Results showed that increasing the resin content from 9 to 11 percent caused MOR, MOE and IB to be increased and thickness swelling after two and 24 hours immersion in water to be decreased. Based on results of this study, most of board properties improved when 11 percent of UF resin was utilized. MOE and T.S. after two hours improved when 6 minutes press time was applied.

CMP and APMP pulping characteristics of corn stalk were investigated. Chemical composition of corn stalks including cellulose, lignin, extractives soluble in alcohol-actone and ash content were measured at %49.67, %21.88, %2.53 and %4.087 respectively. Fiber length, diameter, lumen and cell wall thickness were measured at 0.936mm, 18.463um, 11.59um, and 3.48 um respectively. CMP and APMP pulps were prepared using two pulping temperatures of 90-95 C, cooking times of 20,30,40 and 60 minutes, and NaOH charge at 5 and 10 percent based on oven dry weight of corn stalks. Liquor to corn stalk ratio was constant at 8/1. %3 H2O2 (based on oven dry weight of corn stalks) was used in APMP pulping. The highest CMP yield was obtained with 20 minutes pulping time and these pulps as well as two pulps obtained in 30 and 40 minutes are in group A. The yield of APMP pulp produced with 20 minutes pulping time (pulp yield of %71.1) is in group A and the pulps produced with 30 ,40 and 60 minutes pulping times with average yields at % 70.27, %68.82 and %66.74 are in B,C and D groups respectively. The burst strength of hand sheets produced from these pulps varied between 1.02-1.23 kPa. m²/gr , tear strength between 4.166-4.392 mNm²/gr and breaking length between 4.018- 4.144 Km. This investigation showed that due to limited availabilities of wood, corn stalks can be considered as a potential raw material for pulping development in IRAN.