柚皮纳米微晶纤维素的制备及其用于改进羧甲基淀粉膜性能的研究

以柚皮纤维素为原料，采用硫酸酸解法制备柚皮纳米微晶纤维素，对纳米微晶纤维素的形貌、结晶结构进行表征分析，以复合膜表面形貌、力学性能、水蒸气透过率和透光率为指标，研究不同添加量柚皮纳米微晶纤维素对羧甲基淀粉膜性能的影响。研究发现：柚皮纳米微晶纤维素为长度为60~180 nm，直径为3~15 nm的棒状晶体；X-射线衍射表明其仍为纤维素I型结构；复合膜电镜图光滑平整；纳米微晶纤维素添加量为5%时，复合膜的拉伸强度较原膜提高最大（52.22%）；而随着纳米微晶纤维素的添加，复合膜的断裂伸长率呈下降趋势；当添加量为7%时，复合膜水蒸气透过率降低最大（23%）；纳米微晶纤维素的添加量大于3%时显著降低复合膜的透光率，但未改变原膜在不同波长下的透光率。因此，添加柚皮纳米微晶纤维素能有效改善复合膜的性能，制备出综合性能优良的羧甲基淀粉复合膜。

Preparation of Pomelo Peel Nanocrystalline Cellulose and Its Application in Improving the Properties of Carboxymethyl Starch Film

Nanocrystalline cellulose (NCC) was prepared by sulfuric acid hydrolysis method using pomelo peel as the raw materials. The microstructure and crystal structure of the NCC were investigated. The effects of different NCC additions to carboxymethyl starch films on surface topography, water vapor permeability, light transmittance and mechanical properties of the composite films were investigated. It is revealed that the NCC consisted of rods with lengths ranging from 60 to 180 nm and diameters ranging from 3 to 15 nm. The X-ray diffraction indicates that the crystal structure of NCC is still type I. Scanning electron micrograph shows that the surface of the composite film is smooth and flat. It was found that the tensile strength of the nanocomposite films with 5% (W/W) NCC addition was optimum with an improvement of 52.22%. While the elongation at break of the composite films decreased with the addition of NCC. Water vapor permeability of the nanocomposite films decreased by 23% for the optimum 7% (W/W) NCC content. Although the addition of NCC has reduced the light transmittance of the composite films, it did not change the transmittance of the control films at different wavelengths. Therefore, the additions of NCC to carboxymethyl starch films can effectively improve the performance of the composite films and thus contribute to prepare films with good comprehensive properties.