TEMPO氧化体系选择性氧化未漂非木浆的研究

Study on TEMPO-mediated Oxidation of Unbleached Non-wood Pulps

关键词:  未漂非木浆  TEMPO氧化  纸浆性质  纤维形貌

Key Words:unbleached non-wood pulp  TEMPO-mediated oxidation  pulp property  fiber morphology

摘要:以未漂麦草浆和竹浆为原料,研究了TEMPO-NaBr-NaClO体系氧化前后纸浆性质及纤维形貌的变化情况,并对其氧化过程进行了动力学分析。结果表明,未漂麦草浆和竹浆的TEMPO氧化过程均遵循二级反应动力学方程。经TEMPO氧化后,麦草浆和竹浆的羧基含量大幅提高,分别达569.8 μmol/g和716.7 μmol/g,而纸浆黏度和热稳定性则均显著下降。此外,氧化前后纤维微观形貌、尺寸变化不大,而结晶度则有所增加,但仍保持了天然纤维素I 型的结晶结构。

Abstract:In this study, unbleached wheat straw and bamboo pulps were oxidized by TEMPO-NaBr-NaClO system. Both the fiber morphologies and properties of pulps before and after oxidation were studied. Besides, the kinetics of oxidation process was analyzed. The results showed that both TEMPO-NaClO-NaBr oxidation processes of unbleached wheat straw and bamboo pulps could be described by second-order reaction kinetics equation. After oxidation the contents of carboxyl groups in wheat straw and bamboo pulps increased significantly and reached 569.8 μmol/g and 716.7 μmol/g, respectively. However, the viscosity and thermal stability of the pulps were obviously decreased. Moreover, the microstructure and size of the fibers were almost unchanged before and after the oxidation. The crystalline structure of cellulose Ⅰof the pulps were maintained after oxidation, while the crystalline indices were slightly increased.