SEC-MALLS analysis of softwood kraft pulp using LiCl/1,3-dimethyl-2-imidazolidinone as an eluent
SEC-MALLS analysis of softwood kraft pulp using LiCl/1,3-dimethyl-2-imidazolidinone as an eluent
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DOI：
10.1007/s10570-004-0866-8
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发表时间：
2005-04
期刊：
影响因子：
5.7
通讯作者：
M. Yanagisawa;I. Shibata;A. Isogai
中科院分区：
文献类型：
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作者：
M. Yanagisawa;I. Shibata;A. Isogai
用8%氯化锂/1,3-二甲基-2-咪唑烷酮（LiCl/DMI）和8% LiCl/N，N-二甲基乙酰胺（DMAc）溶液溶解各种纤维素和纸浆样品，并采用多角度光散射检测（SEC-MALLS）对所得到的溶液进行粒径排除色谱分析。虽然SBKP在8%的LiCl/DMAc中不能完全溶解，但1%的LiCl/DMI总能使SBKP在不离心的情况下得到清晰的溶液。使用1% LiCl/DMI作为洗脱液进行SEC-MALLS分析的分子质量（MM）和MM分布测量表明，在相同洗脱体积下，SBKP的MM高于其他纤维素和纸浆样品。SBKP的构象图斜率异常低，为0.41，而其他纤维素和纸浆样品的构象图斜率在0.57 ~ 0.59之间，与正常的随机线圈构象相对应。这些结果表明，在SBKP的高MM区存在一些紧凑的结构，如分支或交联，而不是分子分散状态，当使用LiCl/DMI溶剂体系作为溶剂和SEC-MALLS分析的洗脱液时，可以检测到这些结构。另一方面，包括软木漂白亚硫酸盐纸浆在内的其他纤维素和纸浆样品没有观察到这种结构。因此，SBKP中的致密结构很可能易受酸处理的影响。
Various cellulose and pulp samples including softwood bleached kraft pulp (SBKP) were dissolved in 8% lithium chloride/1,3-dimethyl-2-imidazolidinone (LiCl/DMI) and 8% LiCl/N,N-dimethylacetamide (DMAc), and the obtained solutions were subjected to size-exclusion chromatographic analysis with multi-angle light scattering detection (SEC-MALLS). Although SBKP was not completely soluble in 8% LiCl/DMAc, 1% LiCl/DMI always gave a clear solution of SBKP without centrifugation. Molecular mass (MM) and MM distribution measurements using 1% LiCl/DMI as an eluent for the SEC-MALLS analysis revealed that SBKP had MM higher than those of the other cellulose and pulp samples at the same elution volume. The slope of the conformation plots for SBKP showed an anomalously low value of 0.41, while those for other cellulose and pulp samples were in the range of 0.57–0.59, which corresponds to the normal random coil conformations. These results indicate that some compact structures like branches or cross-linkages other than molecular-dispersed states are present in the high MM region of SBKP, which can be detected when the LiCl/DMI solvent system is used as the solvent as well as the eluent for the SEC-MALLS analysis. On the other hand, no such structures were observed for the other cellulose and pulp samples including softwood bleached sulfite pulps. Thus, the compact structures present in SBKP are likely to be susceptible to acid treatments.