Quantification of water in different states of interaction with wood pulp fibres
Quantification of water in different states of interaction with wood pulp fibres
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DOI：
10.1007/bf02228801
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发表时间：
1996-12
期刊：
影响因子：
5.7
通讯作者：
U. Weise;Thaddeus Maloney;H. Paulapuro
中科院分区：
文献类型：
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作者：
U. Weise;Thaddeus Maloney;H. Paulapuro
湿纸浆中的水的状态在很宽的水分范围内进行了研究，反映了造纸机从压榨部到卷轴的条件。采用两种方法：保水值（WRV）和差示扫描量热法（DSC）。为了提高测量精度，对WRV程序进行了修改。通过在观察到的水分范围内绘制值来直接比较结果。从DSC数据定义了不同类型的水：自由水、冻结结合水和非冻结结合水。在水分布图中绘制水类型与固体含量的关系。这些图表与WRV数据进行了比较。对于所有的纸浆，三个水馏分被发现是相互依赖的，而自由水的去除率下降。水的去除没有发生作为一个独立的水馏分去除序列。细粉和纸浆回收的存在下，发现影响冻结结合水的量，但不冻结结合水。结果表明，在20-75%固含量范围内，所有研究的纸浆的WRV（角质化）都不可逆地降低。该模式对应于存在的游离水的相对量。在固含量超过80- 85%时，冻结结合水消失。由于没有游离水，没有发生进一步的角质化。得出的结论是，WRV似乎是减少了大空隙的纤维素孔壁的粘附关闭。需要水的软化作用来引起结构的“湿角质化”。
The state of water in wet pulps was studied over a wide moisture range, reflecting the conditions on the paper machine from the press section to the reel. Two methods were used: water retention value (WRV) and differential scanning calorimetry (DSC). To increase the measuring accuracy, a modification to the WRV procedure was introduced. The results were directly compared by plotting the values over the observed moisture range. Different types of water were defined from DSC data: free water, freezing bound and non-freezing bound water. The water types were plotted in water distribution charts against the solids content. These charts were compared with the WRV data. For all pulps, the three water fractions were found to be interdependent while the free water removal rate decreased. Water removal did not take place as an independent water fraction removal sequence. The presence of fines and pulp recycling were found to influence the amount of freezing bound water, but not non-freezing bound water. The results showed an irreversible decrease in WRV (hornification) for all investigated pulps in the range of 20–75% solids content. This pattern corresponded to the relative amount of free water present. Freezing bound water disappeared at a solids content of over 80–85%. With the absence of free water, no further hornification occurred. It was concluded that the WRV appears to be reduced by a closure of large voids by adhesion of the cellulosic pore walls. The softening effect of water is required to cause ‘wet hornification’ of the structure.