Abstract The contribution of structural changes of softwood bleached kraft pulp (SBKP) fibers and partly dried SBKP handsheets to their water retention values (WRVs) was studied. Two factors related to mesopores and macropores, which were determined for super critical point (SCP)-dried SBKP sheet samples, should participate in the WRVs determined for wet SBKP sheet samples. The mesopores are formed during pulping/bleaching to remove lignin and a part of hemicelluloses that are present originally in wood cell walls. The combined volumes of mesopores and macropores (totally < ∼0.6 g g−1) in SBKP fibers after SCP drying were significantly lower than the entire WRV (∼1.6 g g−1) of the original never-dried SBKP. We hypothesize that external fibrils of SBKP fibers are formed during pulping, bleaching, washing, pressure-screening, and pressing processes at high and low solid contents in water under high shear forces. The WRV can be used as an indicator to evaluate such structural changes of external fibrils in pulp fibers and paper sheets during drying/wetting in papermaking process as well as in use under various conditions. In contrast, changes in mesopore and macropore volumes determined for SCP-dried sheets cannot properly detect such structural changes of external fibrils.

中文翻译：

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纸浆纤维表面原纤维对保水值的显着贡献

摘要 研究了针叶木漂白牛皮纸浆 (SBKP) 纤维和部分干燥的 SBKP 手抄纸的结构变化对其保水值 (WRV) 的贡献。为超临界点 (SCP) 干燥 SBKP 片材样品确定的与中孔和大孔相关的两个因素应参与为湿 SBKP 片材样品确定的 WRV。中孔是在制浆/漂白过程中形成的，以去除最初存在于木材细胞壁中的木质素和部分半纤维素。SCP 干燥后 SBKP 纤维中中孔和大孔的总体积（总<~0.6 g g-1）显着低于原始未干燥 SBKP 的整个 WRV（~1.6 g g-1）。我们假设 SBKP 纤维的外部原纤维是在制浆、漂白、洗涤、压力筛选、和在高剪切力下在水中高和低固体含量的压制过程。WRV可作为评价造纸过程中干燥/润湿过程中以及在各种条件下使用的纸浆纤维和纸页中外部原纤维的这种结构变化的指标。相比之下，针对 SCP 干燥片材确定的中孔和大孔体积的变化无法正确检测外部原纤维的这种结构变化。