微波辐射法竹浆纤维素的中性TEMPO氧化及表征

Neutral TEMPO Oxidation of Bamboo Cellulose Fiber under Microwave Radiation and Its Characterization

采用微波辐射法和中性2,2,6,6-四甲基哌啶-1-氧化物(TEMPO)自由基氧化工艺来预处理竹浆纤维素,之后用超声波机械处理制备微纤化纤维素。实验结果表明,在60℃下,TEMPO用量为0.15 mmol/g(以绝干浆计,下同),Na Cl O2用量为10 mmol/g,Na Cl O用量为1 mmol/g,微波氧化2 h,其羧基含量最高到达0.729 mmol/g,氧化效果最佳,超声波处理后微纤化纤维素得率高达85.7%。FT-IR分析表明纤维素氧化后引入羧基官能团;XRD结果揭示纤维素氧化反应只发生在纤维素的无定型区或结晶区表面;纤维素氧化前后的聚合度(Dp)结果表明相对于碱性氧化,微波辐射和中性TEMPO氧化对纤维的降解程度低,从而有效地保持了纤维素原本的长度。

The bamboo fibers were pretreated by microwave radiation and neutral 2,2,6,6-tetramethylpiperidinooxy（ TEMPO）oxidation,and then the microfibrillated cellulose was prepared by ultrasonic mechanical treatment. Experimental results showed that the maximal carboxyl content was 0. 729 mmol / g pulp after bamboo fibers were pretreated by 0. 15 mmol / g TEMPO,10 mmol / g NaClO2 and 1 mmol / g Na Cl O at 60 ℃ for 2 h. And the yield of microfibrillated cellulose was 85. 7% after the ultrasonic mechanical treatment. The FT-IR spectra indicated that carboxyl groups were introduced onto cellulose. The XRD analysis indicated that the oxidation reaction was conducted only in the amorphous region or on the crystalline surface area of the cellulose. Meanwhile,the polymerization degree results of the cellulose showed that only minor cellulose fibers were degraded when they were pretreated by microwave radiation and neutral TEMPO oxidation. Therefore,the origin length of fiber was constant through this whole pretreatment process.