Mechanoradical formation and its effects on birch kraft pulp during the preparation of nanofibrillated cellulose with Masuko refining
Mechanoradical formation and its effects on birch kraft pulp during the preparation of nanofibrillated cellulose with Masuko refining
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DOI：
10.1515/hf.2011.183
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发表时间：
2012-05
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通讯作者：
Iina Solala;A. Volperts;A. Andersone;T. Dizhbite;Ņ. Mironova-Ulmane;Annikki Vehniaeinen;J. Péré;T. Vuorinen
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作者：
Iina Solala;A. Volperts;A. Andersone;T. Dizhbite;Ņ. Mironova-Ulmane;Annikki Vehniaeinen;J. Péré;T. Vuorinen
摘要未漂硫酸盐桦木浆的Masuko磨浆比漂白桦木浆的原纤化更彻底。这一结果是通过一次精制纸浆的不同分级行为观察到的，并进一步得到纸浆粘度的不同相对变化的支持。用电子顺磁共振光谱法观察了磨浆过程中机械自由基的形成，并讨论了磨浆过程中木质素和半纤维素的作用[用卡伯值测定和紫外共振拉曼（UVRR）光谱法定量]。木质素是一种已知的抗氧化剂，能够稳定自由基，这可能会抵消高活性纤维素自由基之间的重组反应。另一方面，木质素促进原纤化的能力也可能在于其无定形性质，而不仅仅在于其抗氧化特性。此外，漂白不仅去除木质素，而且去除半纤维素，这影响纤维材料的电荷密度和结构，并且这是含木质素的纸浆更容易原纤化的另一个可能的贡献者。
Abstract Masuko refining of unbleached kraft birch pulp has been noted to result in more thorough fibrillation than the refining of its bleached counterpart. This result is observed through different fractionation behavior of once refined pulps and is further supported by different relative changes in pulp viscosity. The formation of mechanoradicals during refining is observed with electron paramagnetic resonance spectroscopy, and the role of lignin and hemicelluloses [quantified using kappa number determination and UV resonance Raman (UVRR) spectroscopy] in the progress of refining is discussed. Lignin, a known antioxidant, is capable of stabilizing radicals, which could potentially counteract recombination reactions between highly reactive cellulose radicals. On the other hand, lignin’s ability to promote fibrillation could also lie in its amorphous nature and not solely in its antioxidant characteristics. Furthermore, bleaching removes not only lignin but also hemicelluloses, which affects both the charge density and the structure of the fiber material, and this is another likely contributor to the easier fibrillation of lignin-containing pulps.