纤维素纳米晶基彩色膜的增韧改性研究

发布时间：2018-05-04 04:31

本文选题：纤维素纳米晶 + 彩色膜　；参考：《青岛科技大学》2017年硕士论文

【摘要】：本文针对纤维素纳米晶彩色膜韧性差的缺点,采用多种策略对纤维素纳米晶彩色膜进行增韧改性,以期获得具有实用价值的纤维纳米晶彩色膜。借助紫外可见光谱(UV-Vis)、扫描电镜(SEM)、原子力显微镜(AFM)、红外(FTIR)、X射线衍射(XRD)、热失重(TGA)、DMA等表征手段对获得的纳米晶及其增韧后的彩色膜进行表征分析。我们首先采用硫酸酸解法制备了纤维素I晶型的纤维素纳米晶,并结合真空抽滤技术获得均一颜色的纤维素纳米晶彩色膜。并且发现采用真空抽滤技术制备彩色膜时超声时间对彩色膜颜色产生明显影响,随着超声时间延长彩色膜颜色红移,从而可以通过控制超声时间获得所需颜色彩色膜。对获得的彩色膜进行碱处理,之后发现经过碱处理后纤维素纳米晶膜螺旋形液晶结构仍能保留,膜仍保持颜色,并且由于纤维素晶型转化及无定形区含量提高,彩色膜颜色发生明显变化,由于碱处理使纤维素纳米晶发生聚集态结构改变,从而导致彩色膜的韧性得到大幅提高。碱处理也会使纳米晶表面的磺酸根脱除从而使彩色膜的耐热性得到大幅提升。我们还尝试采用真空抽滤法制备纤维纳米晶(CNC)/聚乙烯醇(PVA)的复合彩色膜,经实验发现采用真空抽滤技术可以制备出CNC/PVA复合彩色膜,同时将PVA含量提高后,复合彩色膜颜色并没有像浇铸成膜方式制备彩色膜,颜色发生红移,而是发生蓝移。将获得的复合彩色膜进行碱处理后发现处理后彩色膜螺旋液晶结构仍能保留且与纯CNC彩色膜相似复合彩色膜的机械性能及耐热性得到提升。基于橡胶材料的高弹性,尝试将丁腈胶乳(NBR)加入纤维素纳米晶(CNC)中采用浇铸成膜(Cast)制备复合彩色膜,相比高分子聚合物,球形胶乳粒子加入使得复合彩色膜形成分相结构,形成CNC富集相及NBR富集相。对聚合物而言当CNC与聚合物比例为1:0.6便会失去螺旋液晶结构,而胶乳粒子含量在CNC中比例为1:0.9时仍能保持彩色。同时NBR胶乳加入能够提高彩色膜的机械性能,NBR胶乳包裹住CNC能够改善CNC彩色膜的热稳定性。
[Abstract]:Aiming at the disadvantage of poor toughness of cellulose nanocrystalline color film, various strategies were adopted to toughen and modify cellulose nanocrystalline color film in order to obtain the practical value of fiber nanocrystalline color film. The obtained nanocrystalline and its toughened color films were characterized by UV-VisT, scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) with UV visible spectrum, scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Firstly, cellulose I nanocrystals were prepared by sulfuric acid hydrolysis, and uniform color cellulose nanocrystalline color films were obtained by vacuum filtration. It is also found that ultrasonic time has an obvious effect on the color of color film when it is prepared by vacuum filtration technology. The color of color film can be obtained by controlling ultrasonic time by increasing the color shift of color film with ultrasonic time. After alkali treatment, it was found that the helical liquid crystal structure of cellulose nanocrystalline film could still be retained, and the color of the film was still maintained, and the content of amorphous region was increased due to the conversion of cellulose crystal form and the increase of the content of amorphous region in cellulose nanocrystalline film. The color of color film changed obviously, and the structure of cellulose nanocrystalline was changed due to alkali treatment, which resulted in a great improvement of the toughness of color film. Alkali treatment can also remove sulfonic acid from nanocrystalline surface and greatly improve the heat resistance of color film. We also try to fabricate the composite color film of fiber nanocrystalline CNC/PVA / PVA by vacuum filtration. It is found that the CNC/PVA composite color film can be prepared by vacuum filtration, and the content of PVA is increased. The color of composite color film is not red shift, but blue shift. After alkali treatment, it was found that the helical liquid crystal structure of the color film could still be preserved and the mechanical properties and heat resistance of the composite color film were improved as compared with the pure CNC color film. Based on the high elasticity of rubber materials, the composite color film was prepared by adding nitrile latex (NBR) into cellulose nanocrystalline (CNC). Compared with polymer, spherical latex particles formed the phase separation structure of the composite color film. CNC enrichment phase and NBR enrichment phase were formed. For polymer, when the ratio of CNC to polymer is 1: 0.6, the structure of spiral liquid crystal will be lost, while the content of latex particles in CNC of 1: 0.9 can still maintain color. At the same time, the addition of NBR latex can improve the mechanical properties of color film. NBR latex encapsulated CNC can improve the thermal stability of CNC color film.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ352.7;TB383.2

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