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首页> 外文期刊>Journal of Applied Polymer Science >Dissolution of softwood kraft pulps by direct derivatization in lithium chloride/N,N-dimethylacetamide
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Dissolution of softwood kraft pulps by direct derivatization in lithium chloride/N,N-dimethylacetamide

机译：通过直接衍生化在氯化锂/ N，N-二甲基乙酰胺中溶解软木牛皮纸浆

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摘要

A method for the characterization of the molar mass distributions (MMDs) of softwood kraft pulps dissolved in 0.5% lithium chloride (LiCl)/N,N-dimethylacetamide (DMAc) by size exclusion chromatography is presented. The method is based on derivatization with ethyl isocyanate and the dissolution of samples in 8% LiCl/DMAc. In this study, the derivatization of hardwood kraft pulps did not influence the MMD. In the case of softwood pulps, however, the derivatization decreased the proportion of the high-molecular-mass material and increased the proportion of the low-molecular-mass material, which resulted in a distribution similar to the MMD of a hardwood kraft pulp. The results suggest that associations between hemicellulose and cellulose in the softwood kraft pulp were ruptured during derivatization. This led to a more correct estimation of the MMD of derivatized softwood kraft pulps than obtained by the dissolution of nonderivatized samples. This new method offers several advantages over derivatization with phenyl isocyanate: a precipitation step is not necessary, it is possible to follow the lignin distribution in the samples, and the method allows very high levels of dissolution of softwood kraft pulps up to a kappa number of around 50. (C) 2004 Wiley Periodicals, Inc.
机译：提出了一种通过尺寸排阻色谱法表征溶于0.5％氯化锂（LiCl）/ N，N-二甲基乙酰胺（DMAc）的针叶牛皮纸浆的摩尔质量分布（MMD）的方法。该方法基于异氰酸乙酯的衍生化以及将样品溶解在8％LiCl / DMAc中的方法。在这项研究中，硬木牛皮纸浆的衍生化不会影响MMD。然而，在软木纸浆的情况下，衍生化降低了高分子材料的比例，而增加了低分子材料的比例，这导致其分布类似于硬木牛皮纸浆的MMD。结果表明，软木牛皮纸浆中半纤维素和纤维素之间的缔合在衍生过程中被破坏了。与未衍生样品的溶解相比，这导致了对衍生化软木牛皮纸浆的MMD的更正确估计。与用异氰酸苯酯衍生化相比，这种新方法具有多个优点：不需要沉淀步骤，可以跟踪样品中木质素的分布，并且该方法可以使软木牛皮纸浆的溶解度非常高，直至卡伯值达到大约50岁。（C）2004 Wiley Periodicals，Inc.

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