Iranian Journal of Wood and Paper Science Research
Year:2014 | Volume:29 | Issue:3|Papers Count:15

In this study, optical behavior of methylated and unmethylated Bjorkman lignin from poplar wood and two lignin model compound (phenolic and non phenolic) with b-O-4 linkages was investigated. First, these lignins were precipitated on a cellulosic matrix (Whatman Paper) using different times (0, 5, 10, 15, 20 h) and then matrixcovered surface was analyzed using Attenuated Total Reflectance FTIR technique. The results showed that irradiation altered the chemical structure of all samples. Lignin was the most sensitive component to photodegradation and the intensities of its characteristic bands decreased significantly during the process of irradiation. This was accompanied by formation of new carbonyl groups appearing at 1735 cm-1. Compared with the unmethylated forms, the rate of lignin degradation and carbonyl formation was relatively lower in methylated forms. In other words, methylation of phenolic hydroxyl group reduced the chemical changes induced by irradiation.

In this study, Cationic Pulp Fiber (CPF) was prepared using three levels of 0, 2, 4% (3-chloro-2-hydroxy propyl) trimethyl ammonium chloridein and three temperatures of 40, 60 and 80 oC. Then the CPF fibers were blended with virgin pulp fibers to make handsheets. The results showed that the effect of temperature, CHTMA and CHTMA* temperature interaction on cationizing the fibers was statistically significant. Maximum absorption of cationic CHTMA on pulp fibers with the average of 53.33%was obtained by application of 2% CHTMA at 60 oC temperature. The mixture of 70% long fibers, 30% short fibers, 1% cationized pulp fiber, 5% PCC and three levels of C-PAM (0, 0.05 and 0.1%) was used to prepare handsheets. Freeness of blended pulp and mechanical properties of produced paper such as tensile index, tear index and burst index was determined. Statistical analysis of results showed that the effect of applied treatments was statistically significant. The highest freeness and mechanical properties obtained in different conditions were as follow; freeness (669 mlCSF): CPF 1%, C-PAM 0.05%, PCC 5%; tensile index (15.25 N.m/g): CPF 1%, C-PAM 0.1%, PCC 5%; tear index (12.3 mN.m2/g): CPF 1%, C-PAM 0.1%, PCC 5%; burst index (0.68 kPa.m2/g): CPF 1%, C-PAM 0.05%, PCC 5%.

In this study, GMDH neural network based on genetic algorithm was used to predict the physical and mechanical properties of laboratory made particleboard. To predict the mechanical and physical properties of particleboard we used input parameters such as neural network including press closing time (10, 20 and 30 seconds), moisture content of the mat (8, 10, 12 and 14%) and press temperature (150, 160, 170 and 180oC) as the input data and the output data was the physical and mechanical properties. The efficiency of these techniques was evaluated with statistical criteria of mean square error (MSE), root mean square error, (RMSE), mean absolute deviation (MAD) and the correlation coefficient (R2). Results showed that the value of MSE, RMSE and MAD for MOR, IB, TS24h, TS2h, WA2h and WA24h is low. Errors obtained for the MOE model were very high. According to the results obtained, this model is not the appropriate for prediction of MOE. R2 values from the test and training set properties for MOR, IB, MOE, TS24h, TS2h, WA2h and WA24h was more than 0.91%, which reflects that the performance of these models is better.

The effect of the application of different contents of canola particles in the production of particleboard on its acoustic properties were determined using free vibration on free-free bars procedure.33 samples from each combination of canola and wood particles were prepared and the acoustical properties were determined. Results showed that as the content of canola particles in the mixture of the particles increases, the modulus of elasticity and acoustic coefficient of boards increases from 1260 MPa and 2.34 m4/s.kg to 1560 MPa and 2.54 m4/s.kg respectively. At the lower content of canola particles in the particles mixture, because of inhomogeneity, damping factor increased but by increasing the content of canola particles more homogeneous boards was obtained and damping factor decreased. Also, results showed that significant increase in acoustic coefficient efficiency was reached by increasing the content of canola particles. Therefore as the results revealed, incorporating more canola particles in the particleboard mixture, acoustic properties of particleboard improves and the product can be used in acoustic environments, halls and etc.

In this research, the effects of acetylation on the prevention of white-rot and brown-rot fungi deterioration in medium density fiberboard (MDF) were investigated. Sample boards were made from acetylated poplar fibers, which were treated at different times (0, 30, 90 and 270 minutes) to obtain different weight percent gains (WPGs of 0, 4.85, 9.1, and 15.8%). Totally twelve samples boards at three replication for every treatment were made.. The results were analyzed based on a complete randomized design (CRD) under a factorial experiment. Results revealed that the acetylation decreased the deterioration effect of white-rot and brown-rot fungi. As it was determined, the weight reduction of acetylated boards with the highest WPG (15.8 %) after 16 weeks were measured as 1.605% and 16.93% for white and brown-rot fungi, respectively. It was also determined that the weight loss of the control (untreated boards) samples was measured as 39.96 and 49.31% in the same period. The research results showed that the acetylation enhances biologic resistance in medium density fiberboard.

This research was conducted to investigate the bleaching of combined old newspapers (ONP) and old magazines (OMG) deinked pulp using sodium dithionite. The pulp was bleached using 0.5, 0.75, and 1% sodium dithionite and different times of 30, 60 and 90 minutes. The pulps were then refined to 300 ml, CSF freeness and standard handsheets were made from the refined pulps. The optical and mechanical properties of handsheets and the COD of bleaching effluent were measured according to TAPPI standard test methods. The results showed that the brightness of paper was increased significantly with increase in time and sodium dithionite charge. When the charge of bleaching agent increased, the mechanical properties of handsheets and COD load of bleaching effluent were increased and paper bulk and opacity decreased but these changes were not statistically significant. Increasing the bleaching time from 30 to 90 minutes resulted in a significant improvement in tensile, burst and tear indices but the opacity of paper was reduced.

In this study, the effect of boiling water pre-treatment on yield, optical, physical and mechanical properties of NSSC (Neutral Sulfite Semi Chemical) pulp from Zagroos wheat straw (Golestan province) was investigated. Chopped wheat straw was pretreated in boiling water for 30 minutes, water to straw ratio of 10: 1. NSSC pulping was carried out at constant pulping conditions including liquor to straw ratio of 10: 1, maximum pulping temperature of 160oC and 30 minutes pulping time. In order to study the effect of NaOH on strength properties of paper, in some trails only Na2S03 were used. Pulping was followed by defibration in laboratory refiner to reach 380±25 mlCSF freeness. Handsheets at 60gr/m2 were made from each pulp. The strength properties were determined on the basis of TAPPI standard. Results show that pre-treatment imparted a significant increasing effect on the strength properties of papers such as tensile, burst, breaking length, stiffness and density, except RCT strength. Increasing the chemical charge specially NaOH improved the pulp freeness, yield and handsheet density but the handsheet thickness was reduced.

In this study sound absorption coefficient and hardness of gypsum particleboard produced with kenaf stalk and nano clay were investigated. Variables in this study were weight ratio of kenaf stalks to poplar wood in three levels (40, 50 and 60%) and nano clay content (0, 3 and 6%) based on dried mass of wooden particles. Sound absorption coefficient determined according to ISO 10534-1 and hardness was measured in accordance with the ASTM D-1037 standards. The sound absorption coefficient was measured at four frequencies of 250, 500, 1000, and 2000 Hz. The obtained results showed that with increasing frequencies, sound absorption coefficient increased. With increasing ratio of kenaf stalk in boards, hardness decreased, but sound absorption increased. Furthermore, increase in percentage of nano clay used in the boards increased the hardness and reduced the sound absorption in coefficient in gypsum particleboard. Generally, the highest sound absorption coefficient was shown the boards produced with 60% kenaf and without nano clay in frequencies of 2000 Hz.

In this study, physical properties of composite produced using recycled polymer (polypropylene and polyethylene) filled with two types of paper mill sludge (sludge on the DAF and waste water sludge) were investigated. Three levels of paper sludge (15, 30 and 45 wt%) were used to produce composites. Haake machine was used to blend materials and to produce standard samples; injection molding system was utilized. Density, water absorption and thicknesses swelling of composites were measured. The increasing of both paper mill sludge (sludge on the DAF and wastewater sludge) to the recycled polyethylene and polypropylene increased the density of composites. But, comparing the data obtained from density measurement with literature showed that utilization of paper mill sludge produced relatively lower density and cost on the unit volume basis. Adding both paper mill sludge (sludge on the DAF and waste water sludge) increased water absorption and thicknesses swelling. The samples containing polypropylene and waste water sludge showed lower water absorption and thicknesses swelling compared with other composite.

The effect of old corrugated container (OCC) powder as Urea Formaldehyde resin (UF) filler on the properties of medium density fiberboard (MDF) prepared from bagasse fibers and waste MDF was investigated. The variables in this research were the ratio of UF resin powder to OCC (at five levels; 100: 0, 5.5: 1.98, 97: 3, 5.5: 4.95, and 94: 6) and the ratio of bagasse fibers to waste MDF at five level; 100: 0, 98: 2, 96: 4, 94: 6 and 92: 8).The constant variable in all treatments were 6 mm/min. press closing time and 150oCpress temperature. Thickness swelling (TS), water absorption (WA) after 24h, modulus of elasticity (MOR), modulus of rupture (MOE) and internal bonding (IB)) of panels were measured according to EN standard and statistical analysis was performed using SPSS software. The results showed that OCC powder and MDF waste had significant effect on the bending strength and modulus of elasticity. An increase in OCC improved the internal bonding (IB) while IB was reduced by increasing of MDF waste. Minimum water absorption was found in panels with the maximum waste MDF. This means that the panels with 8 percent waste MDF had the least water absorption. Moreover, the panels with highest content of waste MDF had the least thickness swelling. No significant difference was found between the effects of various OCC powder content on the physical.

In this study, wheat straw-polypropylene particleboard was produced using a mixture of wheat straw and polypropylene with urea formaldehyde resin and its properties were investigated. The ratio of polypropylene to the wheat straw particles was selected as 10: 90, 20: 80 and 30: 70 percent. Urea formaldehyde was used at three levels of 4, 6 and 8 percent based on oven dried weight of wheat straw particle. Mechanical and physical properties (modulus of rupture, modulus of elasticity, internal bonding, water absorption and thickness swelling after 2 and 24h soaking in water) of the produced boards were measured. The results showed that increasing polypropylene and urea formaldehyde resin resulted in increasing the bending strength, modulus of rupture and modulus of elasticity of the boards. The results also indicated that water absorption and thickness swelling after 2 and 24h soaking in water decreased with increased polypropylene and urea formaldehyde resin percent. The UF resin content can be reduced in the particleboard as a function of increasing the PP powder.

Bio and synthetic polymers; micro and recently nano particles have been applied in wet end section of papermaking industry. Very special attention is focused toward their advantages for controlling the process variables and improving the product quality made from recycled papers. In the presence of cationic starch polymer as an anionic trash reducer in the pulp slurry, the effects of cationic polyacrylamide (CPAM) -bentonite nanoparticle complex on retention, drainage and paper properties made from old corrugated container (OCC) was evaluated. The results showed that addition of CPAM polymer individually enhanced burst, tensile and tear strength indices. The application of nano bentonite following CPAM has significantly increased all of mentioned pulp and paper properties. Dewatering rate analysis by Dynamic Drainage Jar and laboratory handsheet maker revealed that the time for the paper manufacturing can be reduced. Moreover, raw material to final product ratio (total retention) increased from 96.7% up to 98.7%. Long chain cationic polyacrylamide shows high capability as the flocculation of papermaking ingredients, individually and particularly in combination with nano bentonite, especially for fines which is a high portion in the recycled pulps. Thus the problem resulting from not retaining sufficient ingredients and the pollution load of the paper mill effluent will be reduced.

This study was conducted with the aim of producing laboratory samples of transparent paper using overbeating method. Hence, bagasse bleached soda pulp was subjected to post-bleaching sequence of DED to remove residual chromophores. Then this pulp was refined in a PFI mill to reach different levels of 55, 130, 200, and 260 mL, CSF (Canadian standard freeness) freeness. Then handsheets were made according to TAPPI standard T 205 om– 8. Results indicated that refining has significant effect on optical properties especially transparency so that the maximum value was observed using pulp with the minimum freeness, i.e.55 ml. The variations of transparency due to refining were also further explained by measuring scattering coefficient, opacity and brightness of the specimens. In addition, mercury porosimetry and analyzing the pictures of scanning electron microscopy (SEM) demonstrated the extensive variations of pore structure in paper during refining which impose great influence on developing transparency.

Microbiological degradation of wood and wood products is one of the most important of disadvantage which reduce its useful life. There are various methods to increase the natural durability of wood and wood products and most of them using chemical reagents. In the past, the thermal modification has been used as a ecofriendly method in many times. In this research the effects of steam pretreatment on the fungal durability of particleboard were studied. Steam pre-treatment was applied on the poplar wood particles using a stainless steel reactor at four temperature levels (155, 165, 175 and 185 oc) and three retention times (15, 30 and 45 min). The amount of hemicelluloses, acetone extractives of wood particles as well as EMC and Mass loss of test panels were measured. The results indicated that the steam pretreatment significantly decreased the amount of hemicelluloses of wood particles, EMC and mass loss of test samples where as the amount of extractives of wood particles increased. According to the results, the variation of Mass loss of particleboard test samples showed a significant correlation to the variation of EMC of test samples, hemicelluloses and extractives amount of wood particles when the wood particles thermally pre-treated at 165oC for 30 minutes.

This study was conducted to investigate the effect of Cu nano particles addition on the density profile and mechanical properties of medium density fiberboard. One layer fiberboard (MDF) with the density of 0.58g/cm3 and thickness of 17 mm were produced using Cu nano particles in three levels (5, 10 and 15wt%based on solid content of resin) and urea formaldehyde resin content in two levels (8 and 10wt%based on oven dry weight of fibers) as variable factors. The control panels were produced using 10% resin (based on oven dry weight of fibers) without Cu nano particles using the identical manufacturing parameters as other panels. Mechanical strength including internal bonding (lB), bending strength, modulus of elasticity and density profile using slicing method were determined. The results indicated that increasing the content of Cu nano-particles had no significant effect on the internal bonding as well as bending strength and modulus of elasticity of panels. Increasing the resin content from 8 to 10 percent improved modulus of elasticity (43.7%), bending strength (18.9%) and internal bonding (23%) of panels. In addition, the increasing Cu nano particles up to 5% caused relatively higher IB for panels produced using 8%resin compared to the control panels (containing10% resin) as well as the density profile was more uniform with the lowest differences between maximum and minimum density in the density profile.