Sayed Saeed Shamsi; Amir Khosravani; Mehdi Rahmaninia
Abstract
One of the most common types of paper and paperboard production in Iran, is the production of various grades of liner, test liner and corrugated medium from recycled old corrugated containers (OCC) pulp. With the increase in population, rise of consumption rate and start of new paper production mills, ...
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One of the most common types of paper and paperboard production in Iran, is the production of various grades of liner, test liner and corrugated medium from recycled old corrugated containers (OCC) pulp. With the increase in population, rise of consumption rate and start of new paper production mills, the shortage of raw and fiberous materials in the paper industry is becoming more noticeable. On the other hand, the shortage of wood in the country has been introduced as a driving force for paper recycling industry. Meanwhile, due to the sharp currency fluctuations and the rise in the of imported long fiber price, consumption of virgin fibers as well as imported long fibers has been limited. Therefore, unfortunately, for many reasons, the quality of such paperboards in the most of domestic production mills are not competitive with similar imported products. Therefore, the potential of achieving desirable properties through fiber classification of OCC by Bauer McNett apparatus and removing fine fiber fractions through fractionation (prior to refining) was considered. The results showed that tensile and tear indices increased significantly with the removal of tiny materials such as fines and fillers. This increase was such that the paperboards without fines and fillers not only compensated for the lack of long fibers but also resulted comparable strength properties.
Ehsan Fatehi; Mehdi Rahmaninia; Amir Khosravani; Zeynab Iron
Abstract
In production of paperboards especially the ones with high grammage, limitation of pulp drainage will drastically reduce the speed of papermaking process. In this manner, one of the common ways to improving the drainage and subsequent increasing of machine speed is producing the multilayer paperboards. ...
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In production of paperboards especially the ones with high grammage, limitation of pulp drainage will drastically reduce the speed of papermaking process. In this manner, one of the common ways to improving the drainage and subsequent increasing of machine speed is producing the multilayer paperboards. Although sometimes these layers are connected to each other without applying any additives, but most of the time starch has been applied between the layers for improving the internal bonds of multilayer paperboards. In this study, the effect of spraying two kinds of starch commonly used in industry (native and oxidized starch) with different application dosages (0, 0.5, 1, 1.5 and 2 g/m2) was investigated. The top layer of double layered paperboard was made of recycled printing and writing pulp and the back layer was produced from old corrugated carton (OCC) recycled fibers. Grammage of each layer was set about 100 g/m2. The results showed that spraying native and oxidized starch improved all considered mechanical properties comparing the control sample (without spraying any additive). Also, the native starch indicated better results in comparison with oxidized starch. Moreover, in both native and oxidized starch, the best mechanical properties were observed with applying 1.5 g/m2 of mentioned additives.
Amir Hossein Mehranfar; Amir Khosravani; Mehdi Rahmaninia
Abstract
As the papermaking fibers contain negative charge, therefore some polymer additives used in the pulp slurry, possess counter-ions (cationic polyeletrolyte). Meanwhile, due to increase of electrical conductivity (EC) in the suspension, the performance of many polyelectrolytes encounter some problems. ...
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As the papermaking fibers contain negative charge, therefore some polymer additives used in the pulp slurry, possess counter-ions (cationic polyeletrolyte). Meanwhile, due to increase of electrical conductivity (EC) in the suspension, the performance of many polyelectrolytes encounter some problems. Hence, according to the efforts for the water system closure, less raw water consumption, and therefore higher EC of the pulp suspension, how the performance of polyelectrolyte-based additives such as cationic starch-anionic nanosilica is adversely affected. In this due, the effectiveness of EC on the performance of the mentioned additive combination was investigated. The results confirmed that the EC negatively affected the performance of the wet-end additive system; although the amount of effectiveness was dependent on the type of the pulp property. Such that for low polyelectrolyte dosage and high EC, in certain properties, the positive effect of this additive system was not significant anymore. But, in the case of some other properties such as internal bond and freeness, despite of the negative effects of high EC, the performance of cationic starch-anionic nanosilica system was significantly remarkable.
Narges Ramezani; Amir Khosravani; Hamidreza Rudi
Abstract
Chitosan is one of the biopolymers which possesses unique properties and has been recently considered in various applications such as paper-making. This polymer is soluble in acidic conditions and has the potential to act as a polyelectrolyte under the colloidal condition in the pulp. However, according ...
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Chitosan is one of the biopolymers which possesses unique properties and has been recently considered in various applications such as paper-making. This polymer is soluble in acidic conditions and has the potential to act as a polyelectrolyte under the colloidal condition in the pulp. However, according to the studies, the capability of this polyelectrolyte was better in alkaline condition, in improving the drainage, retention and even strength properties of paper. Therefore, in this study, the performance of chitosan was studied in different conditions and the results were investigated based on the interpretation of the adsorption process and chitosan configuration using silicon wafer model and ellipsometry technique. For this purpose, bleached kraft softwood fibers were refined to a Canadian standard freeness of 300 ml and after addition of chitosan and nano-silica at different pH levels, freeness and fines retention parameters were evaluated. The results of this study confirmed that chitosan polyelectrolyte showed a good performance in increasing drainage and retention at alkaline pH, compared to the other pH levels, lonely and with the addition of nano silica. However in freenes test at acidic pH, the addition of chitosan along with nanosilica reduced the drainage, and no significant effect was observed at neutral and acidic pHs in the case of fine retentions. In order to interpret these observations and to ratiocinate the behavior of chitosan polyelectrolyte, the data obtained from the ellipsometry technique was investigated to determine the configuration and the thickness of the adsorbed chitosan layer which showed a higher thickness of the polymeric adsorbed layer at alkaline pH, and thus, the possibility of the longer tail and loops configurations in the environment and more effective interractions beyond the electrical double layer.
Pulp and paper
Sobhan Jahanshahlou; Amir Khosravani; Mehdi Rahmaninia
Abstract
Production of test liner and fluting from old corrugated containers, is one of the most common paper recycling processes in Iran. This type of papers, have high basis weight and also contain significant fine fibrous and non-fibrous materials; hence, the drainage and in addition, the retention of fine ...
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Production of test liner and fluting from old corrugated containers, is one of the most common paper recycling processes in Iran. This type of papers, have high basis weight and also contain significant fine fibrous and non-fibrous materials; hence, the drainage and in addition, the retention of fine materials, are the obstacles these paper mills may encounter. In these cases, usually application of drainage/retention aids, such as nanoparticle systems can be of much help. In this due, colloidal silica and bentonite are the two of the most commonly used nano-particles with polyelectrolytes in papermaking wet-end. Therefore, in this research, the effect of bentonite and silica sol nano-particles on the performance of cationic starch was compared in terms of drainability, retention and strength properties of paperboard from recycled old corrugated containers. The analysis of the particle size for these two nanoparticles showed that although the thickness of bentonite platelets (maximum 22 nm) was less than nanosilica dimensions (less than 50 nm), the effect of bentonite-cationic starch was not significant in terms of retention, against the nanosilica. Regarding the drainability, following dosing of both silica and bentonite, the parameter much improved (up to 186% in the case of nanosilica). On the other hand, application of cationic starch containing systems in paper handsheets resulted in improvement in tensile and tear indices, however, these properties decreased following addition of nano-particles. Also, internal bonding (Scott- type) incredibly increased (up to 354%) by application of cationic starch and nanosilica. At last, generally in the case of OCC furnish, the nanosilica-cationic starch system had a better performance in terms of drainability, retention of fine materials and fiber fines and also strength properties, rather than cationic starch-bentonite.
