龙须草纤维素的分离与结构表征

Isolation and characterization of cellulose from Chinese alpine rush

采用亚氯酸钠脱木质素,经超声波处理后再用碱抽提出半纤维素,分离得到了龙须草纤维素制备物,探讨了不同碱处理方式对纤维素制备物性质的影响,并对其结构进行了表征。研究发现,采用8%和10%NaOH分级抽提12 h得到的纤维素制备物的纯度最高,纤维素含量为91.3%,平均聚合度为1949,平均分子量为315685。X射线衍射结果表明龙须草纤维素制备物中纤维素的结晶结构为典型的纤维素I结构,在较短的时间(2 h+2 h)内采用较高浓度(15%和18%KOH与NaOH)或在较长的时间(12 h+12 h)内采用较低浓度的碱(8%和10%KOH与NaOH)对脱木质素和超声波处理后的龙须草进行分级抽提,都会导致纤维素结晶度的降低。热分析表明,8%和10%碱分级抽提12 h得到的纤维素制备物的热稳定性优于其他处理方式得到的纤维素制备物。同样的处理方式下,NaOH处理得到的纤维素制备物的热稳定性优于KOH处理得到的纤维素制备物。

The cellulose of Eulaliopsis binata was prepared by delignification with sodium chlorite followed by ultrasonic irradiation and then by extraction with alkali.Effect of extraction methods on the properties of cellulose obtained was investigated and their structure characterized by FT-IR,X-ray diffraction and thermal analysis.The results showed that the product prepared by extraction with 8% and 10% NaOH is of the highest purity,the content of cellulose is 91.3%,average degree of polymerization was 1949,molecular weight was 315685.All the cellulose products are of typical cellulose I structure.The sequential extraction by higher KOH and NaOH concentration（15% and 18%）in shorter time（2 h）or by lower KOH and NaOH concentration（8% and 10%）in longer time（12 h）leads to crystallinity decrease of cellulose products.The thermal stability is better for the cellulose obtained by two-step sequential extractions with 8% and 10% than the others.If treatment method was the same,the thermal stability is better for the cellulose obtained by extraction with NaOH than for the sample by extraction with KOH.