RISE Bioeconomy, Box 5604, SE-11486 Stockholm, Sweden.
Carbohydr Polym. 2020 Feb 15;230:115615. doi: 10.1016/j.carbpol.2019.115615. Epub 2019 Nov 14.
Mechano-sorptive creep, i.e. the increased rate of creep that occurs during changing relative humidity, when loading paper or wood, is a phenomenon still not fully understood. This phenomenon was here investigated by examining the changes occurring at the molecular level utilising FTIR spectroscopy. By subjecting the paper to deuterated water, the changes involving both the crystalline hydroxyls as well as those in accessible regions could be examined. During loading, the cellulose molecular chains are stretched taking the load. In addition, during mechano-sorptive creep a further exchange from OH to OD groups occurred. This was interpreted as caused by slippage between cellulose fibrils allowing previously non-accessible hydroxyls to become available for deuterium exchange. Thus, the loosening of the structure, during the changing moisture conditions, is interpreted as what has led to the increased creep and the possibility for new areas of cellulose fibril/fibril aggregates to be exposed to the deuterium exchange.
机械增塑蠕变，即在改变相对湿度时，纸张或木材受力，会出现蠕变速率增加的现象，这一现象目前尚未被完全理解。本研究利用傅里叶变换红外光谱法，在分子水平上观察发生的变化，以此研究该现象。通过使纸张与重水接触，可以检测到结晶羟基和可及区域的变化。在受力时，纤维素分子链会伸展以承受负载。此外，在机械增塑蠕变过程中，还会发生进一步的从 OH 到 OD 基团的交换。这被解释为由于纤维素原纤维之间的滑移，使得先前不可接近的羟基可用于氘交换。因此，在改变水分条件下，结构的松动被解释为导致蠕变速率增加的原因，并且为纤维素原纤维/原纤维聚集体的新区域暴露于氘交换提供了可能性。
