Document Type : Research Paper
Authors
1 دانشآموخته دکتری مهندسی چوب وPh.D. Graduate in Wood and Cellulosic Products Engineering – Cellulosic Industries, Department of Paper Science and Engineering, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
2 Professor, Dept. of Paper Sciences and Engineering, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
3 Associate Prof., Dept. of Paper Sciences and Engineering, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
4 Associate Prof., Dept. of , Paper Sciences and Engineering, Faculty of Wood and Paper Engineering, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran
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, 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.
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