School of Chemical Science and Engineering, Fibre and Polymer Technology , Royal Institute of Technology , Teknikringen 56-58 , SE-10044 Stockholm , Sweden.
Wallenberg Wood Science Centre (WWSC), Teknikringen 56-58 , SE-10044 Stockholm , Sweden.
Biomacromolecules. 2018 Apr 9;19(4):1245-1255. doi: 10.1021/acs.biomac.8b00088. Epub 2018 Mar 22.
It is demonstrated that the molecular solubility of softwood hemicelluloses is significantly influenced by pretreatment of the fibers, extraction, and downstream processing. To quantify these effects, four hemicellulose samples were extracted from different thermomechanical pulps of Norway spruce. The molecular solubility of the samples was characterized by size and molar mass distributions, and the morphology of the molecules was studied using high resolution microscopy techniques. All extracted samples were well dispersed in aqueous media creating transparent dispersions, but dynamic light scattering measurements showed that molecular solubility can only be achieved using specific pretreatments and extractions. The procedure yields acetylated galactoglucomannan (AcGGM)-rich hemicelluloses with an average molar mass of 21-35 kDa and a diameter up to 10 nm but also shows that water is a poor solvent for this sample since an association is detected as soon as the concentration is about 20 g/L. These associated hemicellulose dispersions are still absolutely clear on visual inspection, underlining the need for careful measurement when assessing the solubility of wood hemicelluloses.
研究表明，木质半纤维素的分子溶解度显著受到纤维预处理、提取和下游加工的影响。为了量化这些影响，从挪威云杉的不同热机械浆中提取了四个半纤维素样品。通过大小和摩尔质量分布对样品的分子溶解度进行了表征，并使用高分辨率显微镜技术研究了分子的形态。所有提取的样品在水介质中均能很好地分散，形成透明的分散体，但动态光散射测量表明，只有使用特定的预处理和提取才能实现分子溶解度。该方法得到的乙酰化半乳甘露聚糖（AcGGM）丰富的半纤维素，平均摩尔质量为 21-35 kDa，直径可达 10nm，但也表明水是该样品的不良溶剂，因为一旦浓度约为 20g/L，就会检测到缔合。这些缔合的半纤维素分散体在目视检查下仍然绝对清澈，这强调了在评估木材半纤维素的溶解度时需要仔细测量。
