Abstract Size exclusion chromatography with multi-angle laser light-scattering detectors was applied for acetylated softwood and hardwood kraft lignins (Ac-SKL and Ac-HKL) and 8-O-4′ type of linear polymeric lignin model (Ac-M-8O4′) to compare their swelling behaviors. The plot of molar mass (MM) vs. retention time for Ac-M-8O4′ was similar to that of polystyrene, which revealed that Ac-M-8O4′ exhibited swelling behavior that was similar to that of polystyrene. However, the MM values of both Ac-KLs were larger than those of polystyrene standards at any retention time. This difference indicated that both Ac-KLs had a more compact structure than those of polystyrene and Ac-M-8O4′. One hypothesis is that the larger MM of both Ac-KLs stems from their branched structures. To verify this hypothesis, the frequency of 5-5′ interunit linkage in lignin samples was determined by 1H NMR after nitrobenzene oxidation. A linear relationship between MM and 5-5′ abundance was observed in the high MM region.

中文翻译：

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对于给定的流体动力学半径，分支结构为牛皮纸木质素提供了更致密的形态和高摩尔质量

摘要 采用多角度激光散射检测器的尺寸排阻色谱法用于乙酰化软木和硬木硫酸盐木质素（Ac-SKL 和 Ac-HKL）和 8-O-4' 型线性聚合物木质素模型（Ac-M-8O4 ') 比较它们的溶胀行为。Ac-M-8O4' 的摩尔质量 (MM) 与保留时间的关系图与聚苯乙烯相似，这表明 Ac-M-8O4' 表现出与聚苯乙烯相似的溶胀行为。然而，在任何保留时间，两种 Ac-KL 的 MM 值都大于聚苯乙烯标准品的 MM 值。这种差异表明两种 Ac-KL 的结构都比聚苯乙烯和 Ac-M-8O4' 的结构更紧凑。一种假设是两个 Ac-KL 的较大 MM 源于它们的分支结构。为了验证这个假设，硝基苯氧化后，通过 1H NMR 测定木质素样品中 5-5' 单元间连接的频率。在高 MM 区域观察到 MM 和 5-5' 丰度之间的线性关系。