基于广角X射线散射技术的竹材纤维素晶型研究

Study of Crystal Structures of Cellulose in Bamboo Using Wide Angle X-ray Scattering Technique

纤维素Ⅰ是自然界中纤维素晶体的主要存在形式,它具有三斜晶体结构的I_α和单斜晶体结构的I_β。为进一步研究竹材中的纤维素晶型,利用同步辐射广角X射线散射(SR—WAXS)技术对毛竹竹壁纤维素晶型进行了初步研究,通过已知的纤维素晶胞模型计算晶面间距并预测衍射峰的峰位,再根据实验所得的实际峰位,判定竹材中纤维素的晶型。结果表明,竹材的衍射峰位与纤维素I_α的理论计算值相近,证明竹材中的纤维素I_β是绝大多数甚至是唯一品型。相比核磁共振技术而言,利用同步辐射广角X射线散射研究竹材中纤维素晶型是一个较为简单的方法。

Cellulose I is the main existence form of cellulose crystal in nature,which consists of two different crystal structures which are marked as cellulose Iα and Iβ.In order to obtain a better and more comprehensive understanding of crystal forms of native cellulose in bamboo culm,Synchrotron Wide Angle X-ray Scattering（SR-WAXS） was used to investigate cellulose polymorphy.The interplanar spacing was calculated and the peak position of the diffraction peaks was predicated through the existed cellulose cell model.And then the crystal structures of cellulose were determined by actual peak position.According to the results,the cellulose Iβ model is in good agreement with experimental values from SR-WAXS peaks,so authors of this paper confirm that the cellulose Iβ is dominant or the unique crystalline structure in bamboo culm.To this extent,it is much convenient to use SR-WAXS to study crystal structures of cellulose than NMR（Nuclear Magnetic Resonance）.