Structural Properties and Potential Applications of Cellulose Nanofiber from Bamboo Shoot Shell

Bamboo shoot shell（BSS）,a by-product from bamboo shoot processing industries,is a natural resource of cellulose. In this study,high-pressure homogenization assisted with acidolysis treatment was employed to produce BSS cellulose nanofiber（CNF）,and the structure was characterized by powder X-ray diffraction（XRD）,Fourier-transform infrared（FT-IR） spectroscopy,atomic force microscopy（AFM）,high resolution transmission electron microscopy（HTTEM）,thermogravimetric analysis（TGA）,and ^13 C nuclear magnetic resonance（NMR）. Moreover,the structure and properties of CNF were compared with those of BSS insoluble dietary fiber（IDF）. The results showed that CNF was in the form of a grid-like micro fiber,and its particle size was obviously reduced,while the crystallinity,thermal stability and solubility were increased. The results indicated that high-pressure homogenization assisted with acidolysis treatment was an effective method to prepare the BSS CNF,which could be a promising biopolymer reinforced material.

Preparation,Structures and Mechanical Properties of Bamboo Shoot Shell Nanofiber/Konjac Glucomannan Aerogels

With bamboo shoot shell nanofibers（BSN） and konjac glucomannan（KGM） as precursor materials, the BSN/KGM aerogels were prepared in different proportions by sol-gel method. The surface morphology, microstructure, characteristic functional groups and thermal properties of BSN/KGM aerogels were characterized by scanning electron microscopy（SEM）, infrared spectroscopy（IR）, X-ray diffraction（XRD） and thermogravimetric analysis（TGA）. The effect of BSN on the structure and properties of BSN/KGM aerogels was also studied. The results showed that the BSN/KGM aerogels possessed network porous structure with compact and homogeneous porosity, high specific surface area and low density. With the increase of BSN, the sheet structure of aerogels was converted into the 3D porous network structure, which contributes significantly higher thermal stability. In addition, the BSN/KGM aerogels showed excellent mechanical properties. The maximum relative compression rate was 62%, suggesting the addition of BSN can enhance the compression properties of the BSN/KGM aerogels.

麻竹笋壳不溶性膳食纤维理化特性及其体外酵解对肠道微生物的影响

以麻竹笋壳为原料,采用化学法提取不溶性膳食纤维(insoluble dietary fiber,IDF),通过高效液相凝胶渗透法、离子色谱法、扫描电镜法、傅里叶红外光谱法鉴定并分析其结构,测定其持水性、溶胀性、持油力、对胆固醇和胆盐的吸附作用,并用体外消化模型评价其对肠道微生物组成的影响。结果表明,麻竹笋壳的IDF拥有较好的水化性质,其持水力和膨胀力分别达到11.26 g/g、8.20 mL/g,持油力达7.56 g/g。提取的不溶性膳食纤维单糖组成以木糖为主,占比达62.70%,具有不规则片状结构,较多皱褶表面使其具备较好的吸附水和葡萄糖分子的功能。IDF在小肠环境比在胃液环境具备更好的结合胆固醇能力以及较好的葡萄糖吸附能力。体外酵解研究表明,发酵24 h后麻竹笋壳的IDF可以提高拟杆菌属、考拉杆菌属相对丰度,有助于调节人体肠道菌群。

竹笋壳研究与应用现状

我国竹资源丰富,竹笋壳作为竹材的次生资源,其收集利用一直被忽视。收集并利用竹林中自然脱落的笋壳和笋加工过程中丢弃的笋壳,不仅可以减少资源浪费,而且可以减少因竹笋壳堆积腐烂而造成的环境污染。文章在介绍竹笋壳结构和化学成分的基础上,分析其开发利用的潜力,综述竹笋壳在吸附材料、食品、纺织、家居等领域的应用现状,并为进一步开发竹笋壳产品提出建议。

几种笋壳的化学成分及其纤维素特征

为探索笋壳纤维的资源化利用途径,采用化学分析、扫描电镜、红外光谱、X-射线和热分析等方法研究其化学成分和结构特征.结果表明：1）笋壳纤维中纤维素、半纤维素含量丰富,分别为36%-40%和35%-46%,木质素仅占1%-8%;2）笋壳纤维呈圆柱形,有沟槽、脊、裂缝和螺旋扭曲;3）笋壳纤维属于典型的纤维素Ⅰ型,在红外光谱中,具有一般纤维素的特征吸收峰;4）经测定,笋壳纤维的结晶度为40%左右,与水稻秸秆纤维类似,但低于棉、麻纤维;5）在热重分析曲线中,笋壳纤维有2个失重阶,在190℃左右开始热分解,主失重温度约为310℃左右.初步研究结果表明笋壳纤维具有一定的开发潜力,可广泛应用于纺织、造纸、复合材料、精细化工等方面.

纤维素纳米晶体对同轴电纺PMMA/PAN复合纳米纤维性能的影响

采用同轴静电纺丝技术,将酸水解获得的纤维素纳米晶体(cellulose nanocrystals,CNCs)添加到聚甲基丙烯酸甲酯(PMMA)/二甲基甲酰胺(DMF)溶液中作为壳层电纺液,聚丙烯腈(PAN)/DMF溶液为核层电纺液,成功制备出核-壳结构的纳米复合纤维。探讨了CNCs添加量对电纺液的电导率和黏度的影响及同轴复合纤维的微观形貌、直径分布、结晶特性、热学性能和疏水性能的影响。结果表明:CNCs添加后电纺液的电导率和黏度有明显提高,所制备的同轴纳米纤维具有较好的核-壳结构,其直径随CNCs加载量的增加而减小,且分布更加集中;添加高结晶度的CNCs后,复合纤维的结晶性得到明显提高;在热学性能方面,CNCs增强的同轴纳米材料最大热分解温度为402.7℃,远高于单纺PMMA和单纺PAN纤维以及未添加CNCs的同轴PMMA/PAN纳米材料;添加亲水性CNCs后,水接触角值由130.0°降低至116.7°,复合纤维的疏水性能明显下降。