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| Study on Dissolution Behavior of Cellulose Fibers from Different Softwood Chemical Pulps inNaOH/Urea Aqueous Solution |
| Received:August 29, 2019 |
| DOI：10.11981/j.issn.1000-6842.2020.02.16 |
| Key Words:softwood pulp;dissolving pulp;pulp fibers;cellulose;dissolution behavior;alkali urea system |
| Fund Project:国家级大学生创新创业训练计划资助项目(201810069029)；天津市企业科技特派员项目（19JCTPJC54900）。 |
| Author Name | Affiliation | Postcode | | 孔维炜* | 天津商业大学包装工程系，天津，300134 | 300134 | | 李慜恒 | 天津商业大学包装工程系，天津，300134 | 300134 | | 寇金宝 | 天津商业大学包装工程系，天津，300134 | 300134 | | 马泽玉 | 天津商业大学包装工程系，天津，300134 | 300134 | | 石岩 | 天津商业大学包装工程系，天津，300134 | 300134 |
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| Abstract: |
| Bleached softwood kraft pulp and softwood dissolving pulp were selected to study in this work, and the difference in dissolution behavior of these two pulps in 7% NaOH/12% urea aqueous solution was investigated by determining transmittance of pulp fiber-cellulose-solvent dissolving system, viscosity of dissolved cellulose solution, observing on the dissolution behavior of pulp fiber by freezing microscope, comparing the changes of fiber length and width before and after dissolution and testing the X-ray diffraction of undisssolved fraction. The results showed that, under the same pulp concentration, the transparency of mixture from dissolution of bleached softwood kraft pulp with higher polymerization degree in 7% NaOH/12% urea aqueous solution was higher than that of the bleached softwood dissolving pulp with lower polymerization degree in 7% NaOH/12% urea aqueous solution. Moreover, the viscosity of the cellulose solution of the former was higher than that of the latter, namely, dissolving pulp with lower polymerization degree and higher cellulose content was more difficult to dissolve in 7% NaOH/12% urea aqueous solution. The fibers of softwood kraft pulp became shorter and thicker after being dissolved, while the fibers of softwood dissolving pulp became longer in length and almost no change in width after being dissolved because of dissolution of most short fibers. The dissolving efficiency of softwood kraft pulp with intact fiber pit structure was better than that of softwood dissolving pulp with cell wall damaged in pulping process because of its better solvent permeability. Contrast to the dissolution of pure cellulose in NaOH/urea aqueous solution, the crystallinity and quality of pulp fiber, the morphology of fiber cells, hemicellulose components and molecular weight distribution of cellulose in pulp fiber all could affect its dissolution behavior in NaOH/ urea aqueous solution. |
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