用桑枝皮提取果胶及制备的纳米纤维素晶须在丝素复合膜中的应用

为高效利用蚕桑资源,以桑叶生产中废弃的桑枝皮为原料,提取果胶并制备纳米级纤维素晶须。研究表明,用0.10mol/L盐酸提取桑枝皮中的果胶,得率最高可达30.1%±1.2%,红外光谱图显示其主要成分为糖醛酸,且不同浓度盐酸处理可提取不同酯化度的果胶;经碱煮后的桑枝皮中的半纤维素和木质素被去除,主要成分为纤维素,再经硫酸水解制备获得长约400 nm、直径约20 nm的纤维素晶须。将桑枝皮纳米纤维素晶须与废弃蚕丝的溶液相混合制备丝素蛋白复合膜,因桑枝皮纤维素晶须与丝素蛋白间具有良好的相容性,故复合膜的强度和弹性模量显著提高,其拉伸强度和杨氏模量分别为35.79MPa和2.10 GPa。初步认为,利用桑枝皮提取果胶和制备纳米纤维素晶须,可以作为提高蚕桑资源利用率与增加桑园产值的途径之一。

Pectin Extraction from Mulberry Bark and Application of Pectin-derived Nano-cellulose Whiskers in Silk Fibroin Composite Film

In order to utilize sericultural resources efficiently, pectin was extracted from the mulberry barks which were discarded in mulberry leaf production and mulberry bark residue after pectin extraction was used to prepare nano-sized cellulose whiskers. The results indicated that the highest yield of pectin was 30.1%±1.2%, which was obtained by using 0.10 mol/L hydrochloric acid for the extraction. Infrared spectrometry of the pectin components displayed that the principal component was alduronic acids. Alkaline cooking had removed hemicellulose and lignin. Main component of the fiber was cellulose. The cellulose whiskers obtained after hydrolysis with sulfuric acid had a length of about 400 nm and a diameter of about 20 nm. The mulberry bark nano-cellulose whiskers were mixed with regenerated silk fibroin solution to fabricate the silk fibroin composite films. There was satisfactory compatibility between mulberry bark cellulose whiskers and silk fibroins. The silk fibroin composite film exhibited significantly improved strength and modulus of elasticity. The tensile strength and Young's module of the composite film reached 35.79 MPa and 2.10 GPa, respectively. It is primarily suggested that pectin extraction from mulberry bark and preparation of nano-fiber whiskers is one of the effective ways to strengthen the utilization efficiency of sericultural resources and to increase the output value of mulberry garden.