Chemical conversion
Chemical conversion
Hojjatullah Akbari; Fatemeh Ravari; Ghasem Asadpur; Ashraf Sadat ghasemi
Abstract
Background and Objectives: The modification of paper components, such as fibers and chemical additives, through the incorporation of specific chemical agents plays a pivotal role in altering or reinforcing intermolecular bonding within the paper matrix. Such modifications can impart novel characteristics ...
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Background and Objectives: The modification of paper components, such as fibers and chemical additives, through the incorporation of specific chemical agents plays a pivotal role in altering or reinforcing intermolecular bonding within the paper matrix. Such modifications can impart novel characteristics that expand the functional applications of cellulose-based materials. The majority of strength-enhancing additives primarily rely on the formation of multiple hydrogen bonds to ensure their retention and effectiveness. Silk sericin, a natural macromolecule, is recognized as an adhesive-like protein. As a hydrophilic biopolymer, sericin exhibits excellent compatibility with other hydrophilic polymers, including starch, polyvinyl alcohol (PVA), and alginate. Due to its versatility and exceptional physicochemical properties, sericin has been extensively utilized in the fabrication of sponges, films, and hydrogels for diverse biomedical applications. The integration of biodegradable materials as alternatives to forest-based resources holds significant importance in the papermaking industry. Although recycled pulp is widely used, a critical challenge remains the reduction in mechanical strength resulting from repeated recycling cycles. This study aims to modify starch and nanocellulose using sericin to exploit its polymeric properties for enhancing the mechanical performance of recycled paper. The research focuses on improving the physical and mechanical characteristics of paper produced from old corrugated container (OCC) pulp.
Material and Methods: This study utilized sericin, nanocellulose, and starch. A nanocellulose-based hydrogel containing sericin was synthesized under controlled laboratory conditions. Functionalization of nanocellulose and starch was achieved via epichlorohydrin (ECH), wherein the hydroxyl groups of these materials reacted with the epoxy groups of ECH. The epoxide-functionalized nanocellulose and starch subsequently reacted with silk sericin, which contains amino acids with active side groups such as amine, carboxyl, and hydroxyl groups, leading to the formation of covalent or hydrogen bonds. The interaction between the amine and amide groups of sericin and the hydroxyl groups of nanocellulose and starch resulted in the establishment of hydrogen bonds, thereby forming the final composite material. The structural modifications of starch and nanocellulose were characterized using instrumental techniques such as Fourier Transform Infrared Spectroscopy (FT-IR), confirming the successful formation of starch-sericin and nanocellulose-sericin compounds. The modified materials were added into recycled pulp at varying ratios to either starch or nancellulose (20/70, 30/70, 40/70, and 50/70), and constant weight of recycled pulp. Handmade paper samples with a grammage of 60 g/m² were produced, and their mechanical properties, including tensile strength index, tear length, burst strength index, tear resistance index, and freeness degree, were evaluated in accordance with relevant standards.
Results: The incorporation of starch and nanocellulose modified with sericin resulted in a statistically significant enhancement of tensile strength, burst strength, and tear resistance in the recycled paper samples. The greatest improvement was observed in the samples containing 20/70 modified starch. The addition of these modified materials positively influenced the mechanical properties of the paper. Given that these additives do not intrinsically alter the inherent strength of the cellulose fibers, the observed changes in tensile strength are likely attributable to an increase or decrease in fiber bonding. This enhancement may stem from the penetration of the applied materials into the interfiber voids, thereby reinforcing the fiber network. Conversely, at higher sericin concentrations, a marginal decline in certain mechanical properties was observed in specific ratios. Tear resistance is a crucial parameter in paper evaluation, influenced by factors such as average fiber length, intrinsic fiber strength, fiber bonding, and fiber orientation. In this study, fiber bonding and orientation were identified as the most significant contributors to the observed mechanical behavior. The incorporation of sericin-modified nanocellulose led to increased air resistance and facilitated a more uniform fiber distribution within the paper structure, indirectly indicating improvements in internal bonding and sheet formation quality. Furthermore, the addition of modified starch and nanocellulose resulted in a reduction in pulp freeness across the tested compositions.
Conclusion: The findings of this study demonstrate the successful bonding of sericin with starch and nanocellulose, leading to structural modifications that improve their functional properties. The utilization of sericin-modified starch and nanocellulose presents an effective and environmentally sustainable approach to enhancing the mechanical performance of recycled paper. This strategy not only improves the overall quality of paper products but also represents a significant advancement toward sustainable development through the utilization of renewable bio-based materials.
Research Paper
Pulp and paper
Soleiman Zaheri; Ali Ghasemian; Mohammadreza Dehghani Firouzabadi; Ghasem Asadpur
Abstract
Background and Objective: Cellulose-based paper is an important renewable resource composed of cellulose, hemicelluloses, and lignin. Due to its advantages, such as lightweight, flexibility, cost-effectiveness, and eco-friendliness, it is widely used. However, paper is inherently flammable. Therefore, ...
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Background and Objective: Cellulose-based paper is an important renewable resource composed of cellulose, hemicelluloses, and lignin. Due to its advantages, such as lightweight, flexibility, cost-effectiveness, and eco-friendliness, it is widely used. However, paper is inherently flammable. Therefore, modifying paper with organic flame retardants is significant for reducing fire hazards and expanding the range of applications for cellulose-based paper. This study investigates the effect of diammonium phosphate and nanoclay combined with cationic starch on the properties of paper produced from soda bagasse pulp.
Materials and Methods: For this purpose, paper was prepared from soda bagasse pulp obtained from Pars Paper Factory with a basis weight of 120 g/m² and an average thickness of 0.185 mm. A coating solution containing 10%, 20%, and 30% of either diammonium phosphate or nanoclay and 10% of cationic starch (totally 6 solutions) were prepared. Then, the paper was coated with 25 milliliters of each solution. The coating process was performed using an Auto Bar Coater, and the samples were dried in an oven at 60–65°C for 10 minutes. After drying, the samples were kept at room temperature for two days. Various tests were conducted, including liquid penetration resistance (Cobb test), thickness, contact angle, tensile strength, bursting strength, and tearing resistance. Additionally, fire-related properties such as thermal stability, burning behavior, and vertical flammability were examined.
Results: Coating paper with diammonium phosphate (DAP) and montmorillonite nanoclay in the presence of cationic starch improved the paper's hydrophobic properties and flame resistance. However, overall, the DAP-coated papers demonstrated better performance compared to those coated with nanoclay. This superiority is due to the formation of uniform layers and the blockage of surface pores, which prevents water penetration and increases hydrophobicity compared to
nanoclay-coated and control samples. The use of DAP at an optimal concentration of 20% increased tensile strength but led to a reduction in tear and burst strength. At higher concentrations, this coating played more effective role in enhancing the mechanical properties of the paper. Increasing the concentration of diammonium phosphate to 30% significantly increased the char yield, indicating improved thermal resistance of the paper. Both coating materials reduced the thermal decomposition temperature and increased the char yield, acting as barriers to prevent further combustion. In vertical flammability tests, DAP-coated papers at higher concentrations exhibited shorter ignition times and lower char lengths, displaying self-extinguishing behavior. The results of Fourier-transform infrared spectroscopy (FTIR) confirmed the flame-retardant performance in the condensed phase. Furthermore, the thermogravimetric analysis (TGA) of the samples showed that the treated samples had the highest char residue percentage compared to the control sample. The flame propagation pattern analysis also indicated improved fire resistance properties in the treated samples compared to the untreated ones. Additionally, all strength properties (such as tensile strength, burst strength, and tear strength) improved in the treated samples. Overall, this study demonstrated that coating with either diammonium phosphate or nanoclay in the presence of cationic starch significantly improves the physical and flame resistance properties of bagasse paper. Notably, using DAP at a 30% concentration increased the char yield to 48.165%, equivalent to a 133% increase compared to the control sample and a 111% increase compared to nanoclay. These findings confirm that modifying paper made from bagasse soda pulp with this combination enables the production of paper with high flame-retardant properties, favorable char yield, and no emission of harmful substances such as halogens or formaldehyde.
Conclusion: Overall, using diammonium phosphate and nanoclay in the presence of cationic starch as a coating material can improve the physical and mechanical properties of bagasse paper, making it more suitable for flame-resistant applications. Thus, these treated paper sheets can be used as fire-resistant paper-based materials.
Research Paper
Wood Modification and Wood Preservation
Mostafa Maleki golandouz; ali Bayatkashkoli; Hadi Gholamiyan; Mahmoud Reza Hosseini Tabatabaei; Saeed Reza farrokhpayam
Abstract
Background and Objective: Date palm is one of the important sources of lignocellulosic materials in southern region of Iran. The structure of date palm wood is a monocot yledonous plant and is very different from the wood of dicot yledonous trees. ،Therefore, an environmentally friendly approach to ...
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Background and Objective: Date palm is one of the important sources of lignocellulosic materials in southern region of Iran. The structure of date palm wood is a monocot yledonous plant and is very different from the wood of dicot yledonous trees. ،Therefore, an environmentally friendly approach to date palm wood modification and the behavior of some mechanical properties for use in the wood and furniture industry was investigated.Materials and Methods: Four date palms branches were collected from Zabol city, Sistan and Baluchestan province. The trunks were cut into four two-meter sections along the length for lightness and ease of transportation in the wood cutting workshop of the Faculty of Natural Resources, Zabol University. Test samples were prepared from different positions along the cross sections and at different heights of the trunk. The aforementioned samples were prepared for mechanical testing and thermal modification. To determine the mechanical properties before modification, tests of tensile strength parallel to the vascular bundles, tensile strength perpendicular to the vascular bundles, shear strength parallel to the vascular bundles, and compressive strength parallel to the vascular bundles were performed. The test specimens were modified for heat treatment in a heat chamber (oven) at 11 different temperatures (120 to 210°C) by maintaining a constant temperature for 2 hours. The some properties including flexural strength, modulus of elasticity, roughness meter, and resistance to screws and nails were tested before and after the thermal modification operation for the suitability in the furniture industry. Analysis of variance of heat treatment was performed at different temperatures. Results: The results showed that the average mechanical properties before modification, tensile strength tests parallel to vascular bundles, tensile strength perpendicular to vascular bundles, shear strength parallel to vascular bundles, and compressive strength parallel to vascular bundles were determined with an average of 85.07, 1.31, 3.58, and 19.79 kg/cm2, respectively. During the modification operation, light smoke and a very fragrant odor with a pleasant aroma were emitted in the laboratory. This phenomenon was one of the signs of changes in the properties of date palm wood after modification. Also, the behavior of some properties, including the bending strength (MOR) of unmodified and modified date palm samples, was recorded with an average of 39.109 and 70.719 kg/cm2, respectively. The highest average modulus of elasticity (MOE) was calculated to be 2356.38 and 2677.57 kg/cm2, respectively. The modification process at different temperatures showed that in the temperature range of 160 oC, an increase in MOR and an increase in MOE occurred. However, with increasing heat treatment temperature in subsequent samples, the MOR and MOE values decreased. In the 210 oC treatment, the samples had almost a superficial burn state. Also, the screw resistance test showed an increase in resistance compared to the nail after modification. The results of the roughness test after modification, in the temperature range of 150 and 160 oC, witnessed a low level of surface changes and smoothness. Conclusion: . This research, can be the beginning of entering into creating basic knowledge for thermal modification of date palm wood. Overall, it offers promising ways to tailor the properties of this lignocellulosic material to suit different applications while maintaining its renewable and environmentally friendly nature. Embracing these advances may pave the way for the development of these innovative and sustainable materials in the wood, furniture, and home interior industries in the coming years.
Research Paper
Chemistry of wood
Mohadeseh Hosseini Someah; Mehrnaz Azadi Boyaghchi; Kambiz Pourtahmasi; Maryam Afsharpour; Samad Nejad Ebrahimi
Abstract
Background and Objectives: Historical papers identification is one of the important stages of studying archival and paper works to ensure its proper conservation. Historical papers consist of fibers with organic carbohydrate compounds such as cellulose and hemicelluloses and lignin. In this identification ...
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Background and Objectives: Historical papers identification is one of the important stages of studying archival and paper works to ensure its proper conservation. Historical papers consist of fibers with organic carbohydrate compounds such as cellulose and hemicelluloses and lignin. In this identification method, the main values mentioned are evaluated and calculated based on the data points and the resulting fraction of the intensity of these main compounds. However, there are components such as lignin in the internal structure and starch in the external structure of historical papers that over time not only lead to damage but are also effective in identification with this method. Many instrumental methods have been used to identify historical papers, including infrared spectroscopy. This research aims to investigate the effect of aging and sizing changes on two types of historical papers known as Samarqand and Daulatabad papers with this device method.
Materials and methods: Among the historical papers, 8 samples were randomly selected. These samples were all selected with the characteristics of self-color and the same starch sizing content, which were measured using Logel's test for this purpose. Artificial aging test was used to investigate the changes in the internal structure of papers as well as the stains on the surface of historical papers, which is an accelerated method of destroying the molecular structure of organic materials of paper. To prepare the samples, about 5 g of historical paper samples D2 and S4 were removed and placed for 24 hours at 23°C and 50% relative humidity. Then they were transferred to the incubator for 24 days for accelerated aging test at 80°C temperature and 65% relative humidity. FTIR Spectroscopy was used in Tehran Art University. This model device is TENSOR 27 made by Bruker, Germany with ZnSe crystal analyzer surface and attenuated total reflection method in the range of 400 cm-1 to 4000 cm-1.
Results: After two cycle of 12 days (576 hours and approximately equivalent to 50 years), the
acidity values in two historical paper samples show a decrease in the pH number value. These values reveal the oxidation of cellulose, which is caused by the combined process of thermal and moisture accelerated aging. The results of increasing the acidity of the papers showed clear peaks in the region of 1730 cm-1 or increased their intensity. These absorption bands correspond to C=O bonds in the carbonyl groups, which were absent compared to the samples before aging and became apparent after aging. The comparison between two historical papers aged for 50 years more than the original paper samples in FTIR-ATR spectroscopy show that after aging, the intensity of cellulose and organic compounds has decreased compared to lignin and with the increase of lignin peak intensity in the region 1595 cm -1 has revealed itself. And these two samples are placed at a higher and farther height compared to their original paper samples, which is due to the increase in the amount of lignin compared to the amount of cellulose and organic compounds. Therefore, the role of aging and change of acidity in the change of fiber identification points according to the Garside diagram is wrong. Also, the effect of the external factor of starch is also shown by the change in wave numbers and their intensity in the main points of 1595 cm-1, 1105 cm-1 and 2900 cm-1. In the spectroscopy of the original paper, the reduction of the peak intensity is quite evident, and this shows that the starch sizing has led to the covering of the paper surface and ultimately the reduction of the intensity of the spectrum. Therefore, by washing the papers, the intensity has changed and the amount of lignin has decreased slightly, but the measure of organic compounds and cellulose has increased.
Conclusion: The result showed that the amount of acidity that appears with the increase of age and with the increase of lignin in historical papers has an effect on the intensity points obtained from FTIR-ATR spectroscopy and shifts them in the Garside diagram. Also, starch sizing is another factor that plays a significant role in changing the data of the Garside diagram in the identification of historical paper fibers and they show different points. Therefore, starch sizing and the aging process, which is related to the change in the amount of acidification of historical papers, affect the FTIR-ATR spectroscopy.
Pulp and Paper
Pulp and paper
Ramin Vaysi; Hossien Resalati; Rabi Behrooze
Abstract
Background and aim: Currently, in Iran, CMP pulp for newsprint production is produced from a mixture of about 50% birch, 20% poplar, and 30% mixtures of other wood species. To improve the strength properties and runability of the papers during production and printing, it is necessary to use about 17% ...
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Background and aim: Currently, in Iran, CMP pulp for newsprint production is produced from a mixture of about 50% birch, 20% poplar, and 30% mixtures of other wood species. To improve the strength properties and runability of the papers during production and printing, it is necessary to use about 17% imported long fibers. This imported pulp, which is usually coniferous kraft pulp and is imported from other countries (Finland), creates dependency and causes large amounts of foreign exchange to be spent and withdrawn from the country annually. On the other hand, in the Behshahr Linter-Pak factory, which is located at a distance of about 50 kilometers from Mazandaran Wood and Paper industries (MWPI), more than 10,000 tons of purified cotton linter are produced annually. Which is of great importance due to its convenient availability, ease and low cost of transporting the material. For this purpose, this research was conducted with the aim of using cotton linter instead of imported long fiber pulp in newsprint.
Materials and methods: To conduct this research, test samples of purified cotton linter from the Behshahr Linter-Pak factory, imported long fiber pulp and CMP pulp from the MWPI were randomly selected. In the first stage, freeness, fiber classification and biometric properties of their fibers were measured. Then, using a PFI mill laboratory refiner, the imported long fiber pulp and cotton linter were refined to the freeness of 500, 450, and 400 CSF, and CMP pulp was refined to freeness of CSF450, 400, and 350 CSF. In the next step, the refined imported long fibers and cotton linters was mixed separately and in proportions of 10, 15, 20, and 25 percent with the CMP pulp of MWPI. The handsheets with the basis weight of 60 gr/m2 were prepared from selected samples and tested according to TAPPI test procedures. A spectrophotometer was used to measure the optical properties of the prepared papers, accordingly, the brightness, yellowness and opacity
of handsheets was determined. Then, the strength properties, especially the tear strength, burst, tensile and breaking length of the handsheets were measured and compared using standard TAPPI tests.
Results: The results of the fiber classification of cotton linter. and imported long pulp showed that the weight percentage of long fibers (14 and 48 meshes) of cotton linter and its dispersion were higher and its fine particles (fines) were lower than imported long fibers. Biometric characteristics of cotton linter fibers and imported long fibers showed that the average fiber length, felting and flexibility coefficients of cotton linter fibers were higher, and their total diameter, lumen diameter, double wall thickness, and Runkel coefficient were lower than those of imported long fibers. Also, with increasing refining revolutions (rpm), the freeness in long fibers and cotton linter showed a decreasing trend. By increasing the percentage of cotton linter and imported long fibers mixed from 10 to 25 percent, the brightness and yellowness of the handsheets improved and its opacity decreased. By adding long fibers and cotton linter and a mixture of cotton linter + long fibers from 10 to 25% to CMP pulp, tensile, burst, tear strengths, and breaking length increased. This increase is milder with the addition of cotton linter to CMP pulp. The paper made from adding cotton linter to CMP pulp has always had the lowest strength properties, and paper made from adding imported long fibers to CMP pulp has had the highest strength properties.
Discussion: Given that cotton linter does not respond well to refining due to its crystalline structure, beater may be more suitable due to its longer and gentle refining. In this regard, the strength properties of paper made from cotton linters have always been lower than those of imported long- fibers. However, the use of a mixture of cotton linter + long fibers, especially in freeness of 400 and 450 CSF, can replace a portion of imported long fibers in newsprint due to its suitable optical and strength properties comparable to imported long fibers.
Pulp and Paper
Pulp and paper
Jafar Ebrahimpour Kasmani; Ahmad Samariha
Abstract
Background and objectives: Paper and cardboard, as biodegradable and lightweight materials, are widely used in the packaging of various industries. Coating paper improves its properties and enhances print quality. Biopolymer coatings have advantages over conventional polymers due to their biodegradability ...
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Background and objectives: Paper and cardboard, as biodegradable and lightweight materials, are widely used in the packaging of various industries. Coating paper improves its properties and enhances print quality. Biopolymer coatings have advantages over conventional polymers due to their biodegradability and non-toxicity. The aim of this study is to prepare a coated cardboard sheet with nanomaterials and mineral compounds as a packaging tool and to evaluate the physical properties and printability of white liner paper from Mazandaran Wood and Paper Company. Various amounts of three materials—nanographene, zein protein, and fluorine—along with an acrylamide resin were used for coating the paper using a blade method. The properties examined included thickness, ash paper content, air permeability, roughness, opacity, whiteness, brightness, yellowness, gloss, optical density, and adhesion. This research investigates the effect of surface coating of cardboard (top liner) with nanographene, protein solutions, and mineral materials. Therefore, the goal of this study is to create a barrier against air permeation by coating the outer surface of the cardboard (top liner) with one or more layers of coating that include nanographene, protein solutions, and mineral materials. This coating is designed as the first layer of the cardboard that is in direct contact with the outside, aiming not only to reduce the interaction between the inside and outside of the cardboard but also to enhance printability.Methodology: The white liner paper with a basis weight of 110 grams was obtained from the Mazandaran Wood and Paper Company. The AO-4 type nanographene was sourced from Graphene Supermarket in the USA, Zein protein from Sigma Aldrich, and fluorine from the Minekavan production group. For coating, nanographene, zein, and fluorine were weighed according to specified weight percentages and mixed with 100 grams of distilled water at 50 degrees celsius for 30 minutes, depending on the treatment conditions. Then, 2.5 grams of styrene-butadiene latex and 0.5 grams of dispersant D200 were added to the mixture and homogenized for 20 minutes at 1500 RPM. A 5% cationic starch solution was also used as a retention aid to enhance the coating. This process resulted in eight different treatments of the white liner paper, each specifically coated with different compositions. The treatments are as follows: Treatment 1, control white liner (CWL); Treatment 2, graphene-coated white liner (WLG); Treatment 3, zein-coated white liner (WLZ); Treatment 4, fluorine-coated white liner (WLF); Treatment 5, graphene and zein-coated white liner (WLZG); Treatment 6, graphene and fluorine-coated white liner (WLFG); Treatment 7, fluorine and zein-coated white liner (WLFZ); Treatment 8, graphene, zein, and fluorine-coated white liner (WLZFG). The physical and optical properties were measured according to standard methods. The experimental design was completely randomized. Data analysis was performed using one-way analysis of variance and Duncan's test at a 95% confidence level.Results: The results of the one-way analysis of variance indicated that there is not a significant difference in thickness, ash content, air permeability, roughness, opacity, whiteness, brightness, yellowness, gloss, and optical density of these papers at a 5% probability level. The greatest thickness is associated with the white liner paper coated with zein and fluorine, while the least thickness belongs to the control sample. Regarding ash content, the highest amount is found in the white liner paper coated with fluorine and graphene. For air permeability, the paper coated with fluorine and nanographene shows the best performance. Roughness results indicate that the white liner paper coated with zein and fluorine has the highest roughness. Additionally, the lowest levels opacity and whiteness are related to the white liner paper coated with zein, nanographene, and fluorine. The adhesion test showed that the coated layers and flexo composite adhered well to the paper.Conclusion: The results obtained from microscopic studies showed that the addition of nanographene, zein, and fluorine improved the quality of the fiber coating on the paper, and using the laboratory coating method allowed for a more uniform surface to be created on the coated paper. A significant increase in paper thickness was observed, attributed to changes in the thickness of the base paper. Air permeability increased significantly with coating, and in some cases, this resistance was so high that it could not be measured. The use of fluorine and zein resulted in maximum roughness, while nanographene produced the least roughness. Additionally, the opacity of the papers decreased after coating. Furthermore, optical density improved in the composite coatings, indicating better print quality. The results suggest that the adhesion of the coating layer to the flexo ink was excellent, and compared to the uncoated samples, the amount of paper delamination was lower. Finally, this study indicates that the use of nanomaterials and biodegradable protein and mineral materials can significantly enhance the printability characteristics of coated papers, making them a suitable alternative to synthetic plastic and polymer materials.
