Chemical conversion
Chemical conversion
hojjatullah akbari; fatemeh ravari; ghasem asadpur; Ashraf Sadat ghasemi
Abstract
AbstractBackground and Objectives:The modification of paper components, including cellulose 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 ...
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AbstractBackground and Objectives:The modification of paper components, including cellulose 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 (Figure 1). 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-derived 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 incorporated into recycled pulp at varying ratios (20/70, 30/70, 40/70, and 50/70), with 70% of the composition consisting 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
AbstractBackground and Objective:Cellulose-based paper is an important renewable resource composed of cellulose, hemicellulose, and lignin. Due to its advantages such as lightweight, flexibility, low cost, and environmental friendliness, it is widely used. However, cellulose-based paper is inherently ...
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AbstractBackground and Objective:Cellulose-based paper is an important renewable resource composed of cellulose, hemicellulose, and lignin. Due to its advantages such as lightweight, flexibility, low cost, and environmental friendliness, it is widely used. However, cellulose-based paper is inherently flammable. As a result, modifying paper with organic flame retardants is of great significance to reduce fire hazards and expand the application range of cellulose-based paper. This study investigates the effect of diammonium phosphate and nanoclay, in combination with cationic starch, on the properties of paper produced from bagasse soda pulp.Materials and Methods:For this purpose, paper was obtained from bagasse soda pulp at Pars Paper Factory, with a basis weight of 120 g/m² and an average thickness of 0.185 mm. The paper was then coated with different concentrations of diammonium phosphate and nanoclay (10, 20, and 30%) along with 10% cationic starch. The coating process was carried out 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 2 days. Various tests were conducted on the samples, including liquid penetration resistance (Cobb test), thickness, contact angle, tensile strength, burst resistance, and tear resistance. Additionally, the fire-related properties of the paper, including thermal stability, burning behavior, and vertical flammability, were evaluated.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 a 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 diammonium phosphate and 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, the use of diammonium phosphate and nanoclay in the presence of cationic starch as coating materials can improve the physical and mechanical properties of bagasse-based paper and make 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
Abstract
Background and Objective: Date palm is one of the important sources of lignocellulosic materials in Iran. The structure of date palm wood is a monocot plant and is very different from the wood of dicot trees. This raw material needed to be studied, therefore, an environmentally friendly approach ...
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Abstract
Background and Objective: Date palm is one of the important sources of lignocellulosic materials in Iran. The structure of date palm wood is a monocot plant and is very different from the wood of dicot trees. This raw material needed to be studied, therefore, an environmentally friendly approach to date palm modification and the behavior of some mechanical properties for use in the wood and furniture industry was investigated.
Materials and Methods: Four date palms were obtained from Sistan and Baluchestan province in Zabol city. The trunks were cut into four two-meter sections along the trunk 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 inside the trunk. The aforementioned samples were prepared and 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 and the same time. The behavior of 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 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: Referring to this research, it is 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 identifying is one of the important stages of studying archival and paper works that ensure its proper conservation. Historical papers consist of fibers with organic carbohydrate compounds such as cellulose and hemicelluloses and lignin. The small amount of ...
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Background and Objectives: Historical papers identifying is one of the important stages of studying archival and paper works that ensure its proper conservation. Historical papers consist of fibers with organic carbohydrate compounds such as cellulose and hemicelluloses and lignin. The small amount of lignin and alkaline fillers has made them last longer. In addition, the presence of Starch Sizing has increased its resistance as it creates a suitable level of writing. 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 with this device method.Materials and methods: Among of 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 company 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 food 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 and newsprint are produced from about 50% birch, 20% poplar, and about 30% mixtures of other wood species. To improve the strength properties and runbility of the papers during production and printing, it is necessary to use about 17% imported long fibers. ...
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Background and aim: Currently, in Iran, CMP pulp and newsprint are produced from about 50% birch, 20% poplar, and about 30% mixtures of other wood species. To improve the strength properties and runbility 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 into Iran 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 in distance 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, imported long fiber pulp and cotton linter were refined to 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 pulp of 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 a basis weight of 60 gr/m2 was prepared from selected samples and according to TAPPI standard tests. 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 classification of cotton linter fibers and imported long fibers 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 rounds (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 gentler 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.
