Iranian Journal of Wood and Paper Science Research
Year:2018 | Volume:33 | Issue:3 (64) |Papers Count:16

Resources conservation and the production of value added products requires the efficient recycling of different paper and board grades especially in writing and printing papers. Mineral fillers application at higher usage in papermaking are foreseen in recycled pulp utilization has recently been investigated. Also the characteristics of recycled fibers and interest in fillers, and in this respect, the application of dry strength additives has been an inevitable strategy. In these regards, the effects of precipitated calcium carbonate (PCC) and Soy Protein (SP) on recycled pulp produced from writing and printing waste papers (mixed office waste) were investigated. SEM micrographs proved the PCC retention which is in accordance with the paper ash content, but the ash content declined at higher filler addition. SP initially improved the retention of fillers present in recycled pulp and also the added PCC retention. Preservation of the filler in recycled paper caused higher total retention due to the presence of SP and the same effect can be reached in simultaneous application of PCC and SP compared to system without SP addition. Polymeric and various functional groups in the SP biopolymer could be attributed for these results. SP application improved freeness (CSF) of the recycled pulp up to 8% which was observed in the highest premixing of SP/PCC (15%). Substituting the recycled fibers by PCC also, significantly improved freeness. PCC application in the all studied levels (10, 12, & 15%) and its premixing by SP reduced the paper water absorbency without statistically significant effect. However, the paper tensile strength index declined by PCC and SP consumption.

During the process of paper production, particularly if mechanical or recycled pulps are used, a large amount of soluble and colloidal substances (DCS) are dispersed or dissolved in the process water. Accumulation of DCS in the mill process water, in particular using closed water system, can lead to many deleterious effects on papermaking process and the quality of the paper products. Therefore, removing or controlling of DCS is quite essential to overcome or reduce the negative effects of these materials. The effect of anionic trash neutralization using different anionic trash neutralizers and pulp washing (to remove anionic trash) on the pulp and paper properties was investigated. After the initial preparation of chemi-mechanical pulps (CMP), bleached kraft pulp and mixing of these pulps with each other, precipitated calcium carbonate (PCC) was added. Then, a cationic retention aid (cationic polyacrylamide) was added to the mixture. To neutralize and reduce the negative effects of anionic trashes, different levels of poly DADMAC with molecular weights of 100000-200000 (0. 025-0. 05-0. 1-0. 15%) and Poly aluminum Chloride (PAC) (0. 1-0. 25-0. 5%) was utilized before adding the retention aids. Although zeta potential, drainage time, and total retention of the pulps were improved by applying different neutralizers, burst index of the paper was marginally reduced which was statistically insignificant. Chemi-mechanical pulp washing and drainage treatment caused the reduction of COD and organic anionic trashes. Washing treatment of the pulp improved drainage time, total retention and reduced burst strength index. According to these findings, using cationic polyelectrolyte can be introduced as a good strategy to reduce the harmful effects of anionic trashes and enhance the retention of suspension components.

In textile industry, the bellow comb fibers are generated in a range length and diameter which can be used as appropriate raw material especially in durable paper production. Therefore, the present study investigate the improvement of durable paper's properties using cellulosic nanofibers in the paper furnish. The below comb fibers and imported chemical pulp wre obtained from company which produces durable papers and were transferred to laboratory. Cellulosic nanofiber was purchase from Nano Novin Polymer Co. and it has been consumed at 4 levels of 0, 0. 3, 0. 6 and 0. 6%. After mixing the pulps with cellulosic nanofiber at determined percentages, handmade at 90 g. m-1 were made and physical and mechanical properties of these papers were evaluated. The results showed that the addition of cellulosic nanofibers up to 0. 9% has led to enhancement of tensile strength, bursting resistance, tearing strength and folding strength comparing to control sample up to 22. 7, 38. 9, 7. 7 and 384% respectively. Increasing the amount of cellulosic nanofibers up to 0. 9%, the surface smoothness has increased up to 7. 9% comparing to control. Moreover, water absorption and pores were reduced as 69 and 7. 9% respectively. The SEM results showed that enhancement of cellulosic nanofiber percentage has led to the reduction of pores.

Nowadays, research on optimum application of natural resources in products manufacturing instead of fossil and non-renewable resources are of utmost importance. Cellulosic resources as the future basis of Green products and also the availability and low cost of minerals, especially in Iran, are appropriate options for various products developing. In this study, the effects of cellulosic fibers and Rockwool fibers (0. 25% and 0. 5%) in the absence and presence of nano bentonite (0. 1% and 0. 2%) on normal and specific properties of Epoxy composite were evaluated. Tensile strength (47. 9 MPa), modulus of rupture (86. 3 MPa) and modulus of elasticity (2100 MPa) of the mineral fiber/epoxy composite and bentonite/epoxy nanocomposite were higher than the cellulosic fiber/epoxy composite. However, cellulosic fiber/epoxy composite showed higher energy absorption of the ballistic impact with lower damaged area caused by the impact compared to rockwool/epoxy composite which provide better protection against the ballistic impact. In the presence of nano bentonite particles in epoxy resin blend, modulus of rupture and elasticity and tensile strength were dependent on the type and amounts of the additives with superiority of the mineral fibers/epoxy nanocomposite compared to the cellulosic fibers. In contrast, the composites energy absorption caused by the ballistic impact and its damaged area were better in cellulosic fibers than the mineral ones. The highest absorbed energy of ballistic impact (60. 7 J) and the least damaged area (10. 7 cm2) were achieved by the highest application of cellulosic fibers (0. 5%) and nano-bentonite (0. 2%).

In this research, the influence of two temperatures (60 and 90° C) and three dosages of sodium hydroxide (5, 7. 5 and 10%, based on the dry weight) on hornbeam wood chips alkaline pre-hydrolysis and soda pulping was studied. Soda pulping of both pre-hydrolyzed and control chips were conducted applying constant pulping variables. The effect of pre-hydrolysis on hemicelluloses removal and sodium hydroxide consumption and pulp characteristic including total yield, reject, pulp freeness, kappa number, and pulp strengths were measured and statically analyzed. In case the effect of variable on measured property was statistically significant, then Duncan multiple range grouping of the measured property was arranged. The result revealed that pre-hydrolysis removed almost 4. 2% (based on dry wood) of hemicelluloses of the wood and pre-hydrolysis demonstrated easier soda pulping delignification, due to weakening the lignin-carbohydrate bonds and both total yield, reject and kappa number were reduced. Tensile strength index of the pulp produced using pre-hydrolyzed chips war lower and as the dosage of sodium hydroxide increases, the tensile strength index was reduced initiated from the removal of hemicelluloses which is also lower than control pulp, Tear strength index of the soda pulp from pre-hydrolyzed chips was mildly reduced which is anticipated to be the consequence of fiber weakening and fiber breaking during cooked chips defibration. The effect of prehydrolysis variables on tear strength was not statistically significant. Based on the result of this study, hornbeam wood can be a potential source of bio-refining based on lignocellulosic material.

Pulp bleaching process involves the final elimination of lignin. Actually, the application of oxygen delignification stage before bleaching process is the essential stage in improving bleaching process and reducing process emission. In this study, the effect of conducting oxygendelignifion process under different process condition, on chemical, physical, mechanical and optical properties of kenaf bast kraft pulp was investigated. The kenaf bast kraft pulp with the kappa number of 22, 1154 ml/g viscosity, and 38% ISO brightness respectively was prepared. Oxygen-delignification g treatments were carried out applying three different temperatures of 90, 100 and 110° C, and two oxygen pressures of 5 and 7 bars, with and without magnesium sulfate addition. Results indicated that oxygen delignification treatment led to intense decrease in pulp kappa number, while the pulp viscosity did not change significantly. Results of measuring delignified pulp viscosity showed that the magnesium sulfate addition prevented the pulp viscosity reduction. Lower temperature had a significant effect on the process improvement, but raising the oxygen pressure did not impart significant effect on the process. Also, the pulp brightness was increased about 7%.

The purpose of this study is to investigate the effect of pH on cellulase enzyme activity measuring drainage and strength properties of OCC pulp. Recycled OCC pulp was pretreated at consistency 0. 4 percent, in constant condition of temperature; 50˚ C, duration 1 hour and pH range of: 4-4. 5, 8-8. 5 applying cellulase enzyme at three levels (0. 1, 0. 3 and 0. 5 percent based on pulp dry weight). The results showed that pretreatment of cellulase enhances the freeness of pulp in comparison with the control samples, but by increasing the concentration of enzyme, the freeness of pulp was reduced in pH: 4-4. 5 the highest freeness was measured at the level of 0. 1 percent and in pH: 8-8. 5 at the level of 0. 3 percent. Also, papers were evaluated for strength properties. The results showed that the increase in the use of cellulase enzyme has increased the tensile and burst strength index. As, in the alkaline pH, the effect of the cellulase enzyme on the increase of these strength was higher than the acid pH. The OCC pulp tear strength index, only in low levels of cellulase enzyme and in acidic pH, increased strength was observed, but with increasing enzyme consumption, there was a decrease in tear strength. Also, for strength to crushing, there was no specific trend regarding the amount of enzyme and pH on enzyme function.

In this research, the effect of using natural poly lactic acid polymer and MAPP coupling agent on the physical and mechanical properties of composite manufactured using sunflower stem flour was studied. For this purpose, three levels of PLA polymer (50, 60 and 70%) and tow levels of MAPP (4 and 6 percent based on dry weight of polymer) were selected as variables. Then, composites were produced and the physical and mechanical properties of the composites including dimensional stability, tensile modulus, flexural modulus and impact resistance were measured. The results showed that increasing the amount of PLA polymer and reducing the portion of sunflower stem flour and increasing MAPP up to 6 percent, increased the flexural, and tensile strength and impact resistances and improved dimensional stability of the composites. I In contrast, the tensile and bending modulus of composites were reduced. However, the results revealed that the physical and mechanical properties of the composites made with this polymer and the sunflower stem flour were comparable with composites made with other polymers and in some cases it was better.

With full respect for the principles of linking wood and conservation project Eldar pine because having good mechanical properties and availability of a wood structure in the form of pavilions chose alcove to the octagon without internal column with computer software Sketch up of Alborz research center with trees and landscaping of the complex was built. In making these structures all stages of the preparation of the wooden parts of drying are quite principled and dried in the open air during the six months were roof wood structure with the use of Eldar pine just Lambe was made in setting up the ceiling of solar connection on an octagonal timber wood using mortise and tenon mode and auxiliary metal was used. Sliding windows can be made to occupy less space. After completion of the period of three months to review the different pieces in different parts of the structure and measurements of physical densities, shrinkage and swelling and mechanical testing of hardness and impact resistance and protection review different parts of the fungal infection and decay structures was investigated. Since shortly after the beginning of the measure is going to change in the early stages of measuring statistically Darnbvdh but in the last stage of a decrease in density of about 5% and reduce the hardness of about 8% were signs of shrinkage and swelling in various parts of it to be seen.

In this research, the effects of vessel features, including vessel diameter, density and porosity on drying rate and casehardening of beech (Fagus Orientalis) and oak (Quercus castaneifolia) woods was investigated. For this purpose, flat-sawn boards with the dimensions of 170×50×80 mm (L×T×R) were cut from the sapwood and then were dried in laboratory kiln at 50˚ C and 50 % relative humidity to final moisture content of 8%. After drying, the severity of casehardening of dried boards was measured using prong test. For anatomical studies and measuring the vessel features, white chalk and black marker method was used and scanned sections were analyzed using Image J. Pearson correlation was applied between vessel features and drying properties using SPSS software. Results showed that vessel proportion and porosity have pronounced effect on the drying rate compared to vessel diameter and the latter feature can be ignored. It was revealed that even though the oak wood vessel diameter is larger, but drying rate in the free-water domain for oak wood was lower compared to beech wood. Results also showed that correlation between casehardening and vessel diameter was significantly positive. However, a negative correlation was observed between porosity and casehardening.

In this study, the comparison on the application between two combination of additives: nano silica with cationic starch and nano cellulose with cationic poly acrylamide on the physical and strength properties of cotton based paper are provided. For this purpose, hydrogen peroxide bleached chemical cotton fibers pulp was made at 45˚ RS and then the additives with specified conditions (cationic starch 1 and 1. 5%, nano silica 0. 3 and 0. 7%, nano cellulose 1, 2 and 3% and cationic poly acrylamide 0. 3, 0. 5 and 0. 7%) were added to the pulp slurry and 70 grams handsheets were made. The paper was evaluated for physical and strength properties. The results indicated that the combination of cationic poly acrylamide and nano cellulose did not much effect on increase majority of cotton pulp strength. The handsheet density, and tensile strength were decreased and tear strength increased and no signification effect on tear strength was observed. The application of cationic and nano silica starch has significantly increased the strength and density properties of pulp handsheets. Therefore, considering the results of physical and mechanical tests, it is possible to use the combination of cationic starch and nano silica to increase the properties of cotton pulp.

In this study Poly vinyl alcohol (PVA) and cellulose nanocrysrals (CNC) composite nanofibers were prepared by electrospinning process. To dissolve PVA, the deionized water was used. The design of experiments (DOE) was based on Taguchi method using the Minitab for optimization of electrospinning. Polymer concentration was determined in 4, 6, 8 and 10% by solvent weight. Bead-free fibers were produced in 8% PVA concentration. CNC were added to polymer in 0. 5, 1, 1. 5 and 2% by PVA weight and DOE was applied for Needle to collector distance (cm), polymer concentration (%), polymer feed rate (mh/hr. ) and applied voltage (Kv) were defined as variables, again to reach the thinnest fibers. Nanocomposites were soaked in GA 50% concentration for 48 hrs. to prevent nanocomposites decomposition. SEM and FESEM were used for morphological characterization. Diameter of the fibers was analyzed by Image software. Tensile, Modulus of Elasticity (MOE), Tension, Porosity, swelling and dissolving of nanocomposites were examined. Chemical reactions were traced by FTIR. Fibers with 87± 16 nm in diameter were achieved in 0. 5% CNC, 22 KV, 0. 3 ml/hr. and 20 cm. Swelling and solubility of nanocomposites were significantly improved by GA. FTIR spectra shows hemiacetal bounds produced during GA soaking. MOE and tensile were improved by CNC addition meanwhile tension and porosity were decreased. Same results were obtained for GA soaked nanocomposites.

In this study, the effect of nano gel wollastonite dosage in three level (0, 5 and 10 percent per dry by weight of the cement) and the mixture ratios of lingocellulosic material to cement in three level (10: 90, 20: 80 and 30: 70) on physical, mechanical, microscopic and biological properties of composite made from rice straw fibers-cement was investigated. Three replicates for each treatment and 27 experimental boards were manufactured. Specimens were prepared according to DIN-EN634 standard test methods to measure mechanical and physical properties. Mechanical and physical properties including static bending strength, modulus of elasticity, internal r bonding(IB), water absorption after 2 and 24 hours immersion in water, density and decay resistant (weight loss ) were measured. Micro-structural properties of composites were evaluated by SEM images. The results showed that, bending strength, modulus of elasticity, internal bonding and density were significantly increased with increasing Nano gel wollastonite. Also, with increasing Nano gel wollastonite, dimensional stability and decay resistance were increased in comparison with the control sample. Results of scanning electron microscopy showed that the calcium hydroxide formed hydrated calcium silicate gel (C-S-H gel) after addition the Nano gel wollastonite. SEM images showed that the micro-structure of the boards was improved by increasing the nano-wollastonite content.