Pulp and paper
Zahra Kazemi Karchangi; Noureddin Nazarnezhad; hasan sharifi
Abstract
abstractBackground and purpose: Today, with the rapid development of human society, the pollution of particles matter (PM) in the atmosphere has increased. Suspended particles easily enter the human respiratory system and have serious effects on health, they are considered as one of the critical and ...
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abstractBackground and purpose: Today, with the rapid development of human society, the pollution of particles matter (PM) in the atmosphere has increased. Suspended particles easily enter the human respiratory system and have serious effects on health, they are considered as one of the critical and risky issues in modern urban societies. Air filters play a key role in reducing the emission of these particles and preventing their harmful effects on human health. Due to the growing importance of air pollution and its harmful effects on human health and the environment, the use of effective and environmentally friendly filters has received more attention. In this regard, natural and biodegradable materials such as bamboo fibers are considered a suitable alternative to synthetic polymer materials in making filters. This research focuses on the preparation and evaluation of cellulose air filter using bamboo fibers to deal with air pollution.Materials and methods: To prepare the filter, bamboo fibers were first pulped through the process of soda anthraquinone with sodium hydroxide 25% of dry weight, pulping time 2 hours and temperature 175 degrees Celsius with 0.2% anthraquinone (AQ), then during D0ED1 sequence was bleached by chlorine dioxide and soda. In the next step, the oxidation process was carried out with 3% hydrogen peroxide, 3% sodium silicate and the ratio of sodium hydroxide to hydrogen peroxide 0.8. Then 3% polyvinyl alcohol was added to the resulting suspension and stirred for 10 minutes with the same retention time for all treatments. The suspension was homogenized with an Ultra Thorax homogenizer and dried in a freeze dryer at -110°C for 72 hours to prepare the cellulose filter.Results: The results showed that oxidation and addition of PVA have a positive effect on the mechanical and structural characteristics of the filter. The tensile strength of filters improved significantly after oxidation and adding PVA and increased from 0.236 Nm/g to 0.528 Nm/g. The amount of porosity and air permeability were also affected by oxidation and PVA addition, after oxidation, the porosity and air permeability increased by increasing the number of carboxyl groups and improving the dispersion of cellulose fibers. While the addition of PVA created strong hydrogen bonds and reduced porosity and air permeability. Electron microscopic images (SEM) also clearly showed the structural changes caused by oxidation. After oxidation and adding PVA, the density of the fiber network increased and improved the uniform dispersion of fibers and created a more coherent structure while small pores between fibers still existed. The specific surface area and the average pore size of the filters were checked using the BET method, which shows that the specific surface area increased in the oxidized and PVA-containing filters, and the pore size was maintained in the nano scale in all filters.Conclusion: These results show that the combination of oxidized bamboo fibers containing PVA leads to the production of efficient air filters with improved characteristics that can help reduce air pollution because these filters are able to prevent the passage of PM suspended particles by having pores at the nanoscale.
Mohamad Bai; Behzad Bazyar; Habibollah Khademi Eslam; Abdolah Najafi; Amir Hooman Hemasi
Abstract
In this study, the effect of cellulose nanofibers and silicon nanoparticles on the properties of nanocomposites made with polyvinyl alcohol was studied and the physical, mechanical and morphological properties of nanocomposites were investigated. Samples were prepared by casting with different ratios ...
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In this study, the effect of cellulose nanofibers and silicon nanoparticles on the properties of nanocomposites made with polyvinyl alcohol was studied and the physical, mechanical and morphological properties of nanocomposites were investigated. Samples were prepared by casting with different ratios of 0, 5 and 10% by weight. The morphology of nanocomposites was examined by scanning electron microscopy. Observations of water vapor permeability and water uptake by adding cellulose and nanoxide oxide nanofibers in pure polyvinyl alcohol control film and nanocomposite films with different compositions were significantly different from each other. Tensile strength of nanocomposites showed that increasing the amount of cellulose nanofibers and silicon nanoparticles increased the tensile strength and the percentage of elongation increased with the addition of cellulose nanofibers and silicon nanoparticles decreased. The results of the present study show that the addition of small amounts of nanocellulose fibers and silicon nanoparticles strengthens the polyvinyl alcohol polymer and improves the physical and mechanical properties and increases the performance of nanocomposites.
Composite wood products
Hadi Ashtari; Mehdi Jonoobi; Maryam Yousefzadeh; Yahya Hamzeh
Abstract
In this study Poly vinyl alcohol (PVA) and cellulose nanocrysrals (CNC) composite nanofibers were prepared by electrospinning process. To dissolve PVA, the deionized water was used due to environmental friendly of PVA. The design of experiments (DOE) was done by the Taguchi method using the Minitab for ...
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In this study Poly vinyl alcohol (PVA) and cellulose nanocrysrals (CNC) composite nanofibers were prepared by electrospinning process. To dissolve PVA, the deionized water was used due to environmental friendly of PVA. The design of experiments (DOE) was done by the Taguchi method using the Minitab for optimization of electrospinning. Polymer concentration was determined in 4, 6, 8 and 10% by solvent weight. Bead-free fibers were produced in 8% PVA concentration. CNC were added to polymer in 0.5, 1, 1.5 and 2% by PVA weight and DOE was applied for Needle to collector distance (cm), polymer concentration (%), polymer feed rate (mh/hr.) and applied voltage (Kv) were defined as variables, again to reach the thinnest fibers. Nanocomposites were soaked in GA 50% concentration for 48 hrs. to prevent nanocomposites decomposition. SEM and FESEM were used for morphological characterization. Diameter of the fibers was analyzed by Image software. Tensile, Modulus of Elasticity (MOE), Tension, Porosity, swelling and dissolving of nanocomposites were examined. Chemical reactions were traced by FTIR. Fibers with 87±16 nm in diameter were achieved in 0.5% CNC, 22 KV, 0.3 ml/hr. and 20 cm. Swelling and and solubility of nanocomposites were significantly improved by GA. FTIR spectra shows hemiacetal bounds produced during GA soaking. MOE and tensile were improved by CNC addition meanwhile tension and porosity were decreased. Same results were obtained for GA soaked nanocomposites.
