A systematic study for the structures and properties of phosphorylated pulp fibers prepared under various conditions
A systematic study for the structures and properties of phosphorylated pulp fibers prepared under various conditions
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DOI：
10.1007/s10570-022-04713-4
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发表时间：
2022-07-12
期刊：
影响因子：
5.7
通讯作者：
Isogai, Akira
中科院分区：
文献类型：
--
作者：
Hou, Gaoyuan;Zhao, Sishun;Isogai, Akira
采用（NH 4）（2）HPO 4和尿素对漂白针叶木硫酸盐浆进行磷酸化反应，在150 ℃下反应0-40 min，首次系统研究了反应时间和（NH 4）（2）HPO 4用量对磷酸化浆结构和性能的影响。随着反应时间的延长，纤维素中的磷和弱酸基团含量及重量回收率均增加，当反应时间为20 min时，磷和弱酸基团的含量分别为1.9和4.5 mmol/g，重量回收率为114%，因此，大量的磷酸酯和弱酸基团被引入到纸浆中，保持了纸浆的纤维形态和纤维素I的晶体结构。结果表明，磷酸化浆中几乎所有的磷酸铵基团都表现为弱酸性。磷酸化纸浆的固态碳-13核磁共振（C-13-NMR）光谱表明，既没有羧基也没有氨基甲酸酯基团在磷酸化纸浆中形成，只有磷酸酯基团被引入到纸浆中的条件下，在本研究中使用。磷酸化纸浆表面的X-射线光电子能谱表明磷酸铵基团通过磷酸化引入纸浆中。较长的反应时间或在磷酸化过程中加入更大量的（NH 4）（2）HPO 4导致较低的水溶胀行为，表明在这些条件下纸浆中发生了一些纤维内和/或纤维间交联。本研究结果表明，磷酸化纸浆纤维适合于制备新的功能性纤维素片材和材料，其中大量的弱酸基团可用作各种离子交换位点的支架。[图形]。
A bleached softwood kraft pulp was phosphorylated with (NH4)(2)HPO4 and urea at 150 degrees C for 0-40 min, and the structures and properties of the resulting phosphorylated pulps were systematically investigated for the first time in terms of reaction time and the amount of (NH4)(2)HPO4 added. The phosphorous and weak acid group contents, and the weight recovery ratio increased with increasing reaction time, and were 1.9 and 4 5 mmol/g, and 114%, respectively, when the reaction time was 20 min. Therefore, numerous phosphate ester and weak acid groups were introduced into the pulp, maintaining its fibrous morphology and cellulose I crystal structure. It was found that almost all the ammonium phosphate groups in the phosphorylated pulp behaved as weak acids. The solid-state carbon-13 nuclear magnetic resonance (C-13-NMR) spectrum of the phosphorylated pulp showed that neither carboxy nor carbamate groups were formed in the phosphorylated pulp; only phosphate ester groups were introduced into the pulp under the conditions used in the present study. The X-ray photoelectron spectra of the phosphorylated pulp surfaces suggested that ammonium phosphate groups were introduced into the pulp by phosphorylation. A longer reaction time or a greater amount of (NH4)(2)HPO4 added during phosphorylation resulted in lower water swelling behavior, indicating that some intrafiber and/or interfiber crosslinking occurred in the pulp under these conditions. The results obtained in the present study show that phosphorylated pulp fibers are suitable for the preparation of new functional cellulosic sheets and materials, in which large amounts of weak acid groups can be used as scaffolds for diverse ion-exchange sites.[GRAPHICS].