Document Type : Research Paper
Authors
1 Ph.D. Student, Dept. of Paper Sciences and Engineering, Faculty of Wood and Paper Engineering
2 Assistant Prof. of Pulp and Paper Technology, GUASNR, Faculty of Wood and Paper Engineering, Dept. of Wood and Paper Industries
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 Wood and Paper Science Department, Faculty of Natural Resources, Sari Agricultural Sciences and Natural Resource University Sari, Iran
Abstract
Background and Objectives: Plastic packaging is considered one of the most important sources of environmental problems due to its slow decomposition. To address this issue, biomaterials have garnered attention for their quick decomposition and renewability. In this context, the use of cellulose fibers in packaging is preferred over plastic. However, the main challenge of using cellulose fibers in packaging production is their poor water resistance. This issue can be improved with a suitable bio-coating, which has inspired the current study. The aim of this study was to use a simple method to prepare hydrophobic paper that is environmentally friendly with a biopolymer.
Methodology: The raw material used to make handsheets was bleached softwood Kraft pulp from the Pars paper mill. The Canadian Standard Freeness (CSF) of refined paper decreased from 750 ml CSF to 350 ml CSF. To enhance strength properties, the fibers were treated with carboxymethylcellulose (CMC) in the presence of electrolyte (CaCl2). A suspension of untreated (70%) (LF) and CMC-treated (30%) cellulose fibers was used to make handsheet paper (MLF) with a grammage of 60 g/m2. To prepare the emulsion, beeswax was melted in hot water at different concentrations (1, 5, 10, 15, and 20%), then dispersed in water using ultrasound for 9 minutes with an amplitude of 100. The paper was air-dried, immersed in different concentrations of beeswax emulsion, and then heat-treated at various temperatures (25, 60, 70, 80, and 90 ⁰C). The effect of thermal treatment on the efficiency of beeswax was examined by measuring water absorbency time and water contact angle for all treatments, with 70 ⁰C identified as the optimal temperature. The next step is to evaluate the effect of different concentrations of beeswax on properties such as water absorption (cobb), thickness, grammage, tensile strength index, brightness, and opacity.
Results: Compared to untreated paper, the water absorbency time and water contact angle of all paper treated with different concentrations of beeswax at various temperatures (25, 60, 70, 80, and 90 ⁰C) increased significantly. The contact angle of handsheets treated with beeswax increased significantly with the temperature of thermal treatment. The highest water contact angle was achieved with handsheets immersed in 20% beeswax and heat-treated at 70 ⁰C. However, further increases in temperature beyond 70 ⁰C did not significantly affect the water contact angle of the paper samples. The water absorption in LF and MLF papers was 65.96 g/m2 and 7.96 g/m2, respectively. Treatment with beeswax reduced the water absorption rate compared to the control treatment at all concentrations. Paper coating increased the thickness and grammage of the paper, which increased with higher concentrations of beeswax emulsion. The tensile strength index increased after using modified fibers with CMC compared to LF paper, but coating with beeswax emulsion decreased the tensile strength index of the paper. MLF treatment and beeswax-coated paper had higher brightness compared to LF paper. Immersion in beeswax slightly decreased opacity, but this change was not statistically significant.
Conclusion: The results indicate that the barrier characteristics in samples covered with beeswax improved compared to the blank sample. The study demonstrates the efficient, simple, and cost-effective production of hydrophobic paper as a biodegradable material. A key advantage of this method is the absence of chemicals containing flora or organic solvents in the preparation, making it suitable for industrial applications and meeting the requirements for sustainable development through the use of green ingredients.
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