TEMPO氧化莱赛尔纤维的分子量及官能团分布研究

Molecular weight distribution and functional group profiles of TEMPO-oxidized lyocell fibers

使用TEMPO催化氧化体系处理莱赛尔纤维，TEMPO氧化体系由NaClO、NaBr及2,2,6,6-四甲基哌啶-1-氧自由基（TEMPO）构成。通过凝胶渗透色谱（GPC）和基团选择性荧光标记研究TEMPO氧化的影响，该方法不仅能测定官能团含量，同时还能得到与纤维素纤维分子量相关的官能团分布情况。对醛基、羧基分布情况以及分子量变化的分析表明TEMPO氧化1h内平均分子量显著下降，而继续延长氧化时间并不会引起更多链断裂。通过使用较高浓度NaClO （2.42～9.67mmol/g纤维）反应1h或更长时间能够向高分子量部分引入大量的羧基。

The effects of TEMPO-mediated oxidation, performed with NaClO, a catalytic amount of NaBr, and 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO), were studied on lyocell ifbers by means of GPC using multiple detection and group-selective lfuorescence labeling according to the CCOA and FDAM methodology. The applied method determines functional group content as a sum parameter, as well as functional group proifles in relation to the molecular weight of the cellulose ifbers. Both the CHO and COOH proifles, as well as molecular weight alterations, were analyzed. A signiifcant decrease in the average molecular weight was obtained during the ifrst hour of TEMPO-mediated oxidation, but prolonged oxidation time resulted in no strong additional chain scission. Signiifcant amounts of COOH groups were introduced in the high molecular weight fractions by the oxidation with higher concentrations of NaClO (2.42-9.67 mmol NaClO/g ifber) after modiifcation times of 1 h or longer.