Pulp and paper
Esmaeil Rasooly Garmaroody; Omid Esmaeili; Sead Rahman jafari Petrody
Abstract
Background and purpose: Paying attention to the resistance properties of paper during its production and consumption has always been particularly fashionable for paper makers. In the case of NSSC pulp, it is very important to maintain its resistance and continuous production for the production of floating ...
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Background and purpose: Paying attention to the resistance properties of paper during its production and consumption has always been particularly fashionable for paper makers. In the case of NSSC pulp, it is very important to maintain its resistance and continuous production for the production of floating papers or the combination in the production of various types of liner paper. The use of recycled papers in pure form or in combination with virgin papers has shown that the resistance properties of the resulting papers are reduced. Therefore, in order to use recycled paper, either pure or combined with virgin pulp, it is necessary to take measures to improve the quality of the final paper.Materials and methods: This research was conducted to investigate the effects of using oxidation methods with hydrogen peroxide and hypochlorite to monitor the characteristics of congress corrugated pulp by combining NSSC and OCC pulps. In this research, firstly, the desired pulps were oxidized using hydrogen peroxide and sodium hypochlorite in different proportions, and then according to the TAPPI standard, handmade papers of 127 g/cm2 were made from them. Finally, the mentioned papers in terms of physical characteristics such as Cobb-60 and Air resistance; And the mechanical strength were evaluatedResults: The control treatments have more water absorption resistance and its amount decreases with the oxidation treatment of the pulps. Papers obtained from pulps oxidized with hypochlorite have more resistance to air passage than with peroxide. In this sense, the paper obtained from pure OCC treatment has the lowest air resistance. Papers obtained from pulps oxidized with peroxide have more tear index. Therefore, it seems that peroxide is preferred in terms of tearing properties compared to hypochlorite. In most cases, papers obtained from hypochlorite treatment have more tensile index. The use of oxidation with hypochlorite increases the forld resistance. In terms of CMT, RCT and CCT resistances, combined oxidation processes have been more effective, especially in treatments containing long fibers. The effect of oxidation with peroxide and hypochlorite on the resistance of the paper surface in NSSC and OCC papers are completely different and act in the opposite direction. But in combined treatments, more CMT is obtained. The effect of both oxidants on the characteristics of resistance to ring crushing (RCT) in NSSC and OCC papers in pure treatments has an upward trend, and in the combined state, it causes a decrease in RCT in the papers. The effect of oxidation with hypochlorite on the paper edge cramp resistance (CCT) has been higher compared to peroxideConclusion: The use of oxidation treatment with peroxide for all pulps makes the resulting papers have a higher tearing index. However, in the use of hypochlorite, the resistance characteristics affected by the bond between fibers, such as tensile strength and folding resistance, have been improved. In terms of resistance characteristics such as CMT, RCT and CCT resistance, the combination of peroxide and hypochlorite treatments along with long fibers have been more effective, therefore, considering the importance of these characteristics in the production of congress paper, it is suggested that these treatments should be prioritized.
Composite wood products
ghasem asadpour; seyyed majid zabihzadeh; Maryam Ghorbani; mahmoud davoudi
Abstract
Current research was conducted to investigate the effect of thermal modification on practical properties of horn beam bark flour-polypropylene composites. Wood plastic composites were divided in two levels of control and thermal modification, both levels included of 4 groups in bark fillers; 10, 20, ...
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Current research was conducted to investigate the effect of thermal modification on practical properties of horn beam bark flour-polypropylene composites. Wood plastic composites were divided in two levels of control and thermal modification, both levels included of 4 groups in bark fillers; 10, 20, 30 and 40%. Test samples prepared with maleic anhydride-grafted polypropylene as coupling agent by injection molding method. According to the results, bark flour increased water absorption, tensile and bending modulus. High proportion of bark fillers declined mechanical strength. Thermal modification significantly improved physical and mechanical properties of composite. Using lignocellulosic material flour bark hornbeam, tensile modulus and flexural modulus of composite material background had the highest improvement. In comparison between mechanical properties, impact resistance by adding flour bark had the greatest decrease. Thermal modification by increasing the crystallity, hemicellulose degradation, loss of polarity, increased compatibility between the two phases and uniform distribution of bark fillers in polymers, increased mechanical resistance.
Pulp and paper
masoumeh mollaei; Mohammad Azadfallah; Yahya Hamzeh; faramarz khodaian chegini
Abstract
The Effect of Chitosan - Poly (vinyl alcohol) Coatings on Strength and Barrier Properties of Packaging PaperAbstract In this research the mechanical and barrier properties of hand-sheets made of virgin and recycled fibers were studied after coating by chitosan and poly (vinyl alcohol) polymer blends. ...
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The Effect of Chitosan - Poly (vinyl alcohol) Coatings on Strength and Barrier Properties of Packaging PaperAbstract In this research the mechanical and barrier properties of hand-sheets made of virgin and recycled fibers were studied after coating by chitosan and poly (vinyl alcohol) polymer blends. Therefore to evaluate coatings effects on barrier properties, water vapor transmission rate (WVTR), water absorbance, air resistance and grease proof of coated papers were determined. Moreover, mechanical strength including tensile strength and burst strength were measured. According to the results, the barrier properties and mechanical strength of coated papers improved dramatically than uncoated ones. The best results in WVTR and mechanical strength tests were obtained for coatings with the same ratio of polymers. On the other hand, coating with 75%chitosan - 25% poly (vinyl alcohol) composition exhibited excellent resistance against the grease penetration and water absorption.Keywords: Coating, chitosan, poly (vinyl alcohol), barrier properties, mechanical strength
Pulp and paper
Farzaneh Shiralizadeh; Sahab Hejazi; Mohammad Ahmadi
Abstract
In this research, rice straw was used as raw material. Potassium hydroxide was combined with monoethanolamine (MEA) as liquor. In another processes NaOH/Na2So3, KOH/K2So3 and KOH 14% was used as references pulp. The results showed that using pure MEA(15%) produced the highest yield and the highest kappa ...
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In this research, rice straw was used as raw material. Potassium hydroxide was combined with monoethanolamine (MEA) as liquor. In another processes NaOH/Na2So3, KOH/K2So3 and KOH 14% was used as references pulp. The results showed that using pure MEA(15%) produced the highest yield and the highest kappa number. By using potassium hydroxide as a additive agent in MEA pulping, the amount of reject, yield and kappa number was decreased and the lowest yield and the lowest kappa number relevant to MEA(15%) combined with KOH (40%). In addition, in KOH pulping observed that, with increasing concentration of MEA, as additive agent, the amount of total yield increased but the kappa number and reject content was decreased. Results showed that the highest tensile index and tear index were relevant to MEA (15%) combined with KOH (20%) and the highest burs index relevant to NaOH/Na2SO3 treatment. According to the optical properties, it was found that the highest brightness was achieved in K2SO3/KOH. The highest opacity relevant to the KOH14% .The result shows that MEA process in combined with Potassium hydroxide can be done success fully on rice straw and properties of pulp production, specially in aspect of mechanical strength, in term of combination is superior than soda and Potassium hydroxide process
Composite wood products
Hamid reza Adalat; Taghi Tabarsa; Marzyeh Raeisi
Abstract
For this study 10 logs of Paullowina.furtunie from Shastkalateh forest of Gorgan in Iran were selected randomly. After that, 45 clear flat swan specimens prepared and dried to 5% moisture. Density of each log and thickness of specimens were measured. Three levels of compression percent (16%, 33% and ...
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For this study 10 logs of Paullowina.furtunie from Shastkalateh forest of Gorgan in Iran were selected randomly. After that, 45 clear flat swan specimens prepared and dried to 5% moisture. Density of each log and thickness of specimens were measured. Three levels of compression percent (16%, 33% and 50%) and temperature (130°C, 145°C and 160°C) were the variables. The physical properties of specimens such as spring back, compression set and thickness swelling were calculated. Also, MOE, MOR and impact resistance of specimens were evaluated. In order to have accurate examination, microscopic images were taken. Results show that, with increasing in compression percent, the amounts of spring back and thickness swelling enhance. Densification with 16% compression, yields deformation in elastic region while 33% and 50% compression, causes more compression set. The more compression percent, the more mechanical strengths and the highest strength attained in 50% compression. The effect of temperature was insignificant mostly. Finally, the proper treatment for Paullownia densification, was 130°C and 50% compression. Microscopic images asserted the above results and illustrated that, the enhancing of densification above 50% compression is possible.
