固液相法纤维素氨基甲酸酯及其再生纤维素膜制备与表征
发布时间：2019-03-10 21:48
【摘要】：纤维素被认为是目前为止最有潜力替代化石能源的天然高分子;广泛应用于食品、能源、材料等行业。纤维素内部存在发达的氢键网络,使得纤维素很难被溶解和熔融,使纤维素在加工和应用方面受到了限制。为了能够使纤维素溶解在一般溶剂中,并探索出一条低成本、绿色、环保的工艺路线;本研究中,使用廉价、高沸点、非质子、极性溶剂N,N-二甲基乙酰胺(DMAC)为介质,以纤维素和尿素为原料,通过酯化反应制备了纤维素氨基甲酸酯(CC),采用傅里叶变换红外光谱仪(FTIR)、X-射线衍射仪(XRD)、~(13)C-核磁共振仪(~(13)C-NMR)、热重分析仪(TG)、扫描电子显微镜(SEM)和偏光显微镜等仪器对产物进行性能表征;对CC的制备条件、溶解性能、CC溶液的流变性能以及其再生膜的性能进行了研究。FTIR和~(13)C-NMR测试表明,在DMAC体系中,成功合成了 CC;在该体系中,制备CC的最佳条件为:反应温度为160℃,反应时间为6h,碱纤维素、尿素和DMAC的最佳质量比为1:4:16。XRD测试结果表明,在DMAC体系中酯化前后,纤维素的晶型没有发生变化,结晶度略有降低;通过稀H2SO4凝固浴再生后得到的纤维素再生膜,膜的晶型和碱纤维素的晶型一样属于纤维素Ⅱ晶型结构,而再生膜的结晶度有所降低。TG测试表明,酯化后纤维素的热稳定性略有降低;再生过程中,纤维素再生膜的结晶度有所降低,由于再生膜中存在的金属阳离子Na+能够催化氧化纤维素,使得纤维素再生膜的热稳定降低。流变测试表明,CC溶液为假塑性流体,随着温度的升高,溶液的粘度先降低再升高;在相同的剪切速率下,CC质量分数越高的溶液,其粘度越大,凝胶温度越低,溶液越不稳定。SEM测试结果表明,在DMAC的作用下,通过纤维素酯化反应,纤维素表面的结构遭到破坏,表面裂纹增加,变得粗糙,略有剥落。对于纤维素再生膜,用质量分数越低的稀H2SO4凝固浴制备的纤维素再生膜,其表面更加粗糙,表面孔更多,用质量分数越高的稀H2SO4凝固浴制备的纤维素再生膜,其表面更加致密。纤维素再生膜的过滤性能测试表明,膜的纯水通量随着压力的增加而增加,随着凝固浴中H2SO4的质量分数的增加而降低。用质量分数为5%的稀H2SO4凝固浴制备的纤维素再生膜对亚甲基蓝的截留率高达97.5%。因而纤维素再生膜在印染废水处理方面有很好的应用前景。
[Abstract]:Cellulose is considered to be the most potential substitute for fossil energy by far; widely used in food, energy, materials and other industries. There is a well-developed hydrogen bond network in cellulose, which makes it difficult to dissolve and melt cellulose, which limits the processing and application of cellulose. In order to make cellulose dissolved in general solvent, and explore a low-cost, green, environmentally friendly process route; In this study, cellulose carbamate (CC), was prepared by esterification of cellulose and urea using cheap, high boiling point, non-proton, polar solvent N, N-dimethylacetamide (DMAC) as medium. Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), ~ (13) C-nuclear magnetic resonance instrument (~ (13) C-NMR), thermogravimetric analyzer (TG), The products were characterized by scanning electron microscope (SEM) and polarized light microscope (POM). The preparation conditions, solubility, rheological properties of CC solution and the properties of regenerated membranes of CC were studied. FTIR and ~ (13) C-NMR measurements showed that CC; was successfully synthesized in DMAC system. In this system, the optimum conditions for the preparation of CC are as follows: reaction temperature is 160 鈩，
本文编号：2438062
[Abstract]:Cellulose is considered to be the most potential substitute for fossil energy by far; widely used in food, energy, materials and other industries. There is a well-developed hydrogen bond network in cellulose, which makes it difficult to dissolve and melt cellulose, which limits the processing and application of cellulose. In order to make cellulose dissolved in general solvent, and explore a low-cost, green, environmentally friendly process route; In this study, cellulose carbamate (CC), was prepared by esterification of cellulose and urea using cheap, high boiling point, non-proton, polar solvent N, N-dimethylacetamide (DMAC) as medium. Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), ~ (13) C-nuclear magnetic resonance instrument (~ (13) C-NMR), thermogravimetric analyzer (TG), The products were characterized by scanning electron microscope (SEM) and polarized light microscope (POM). The preparation conditions, solubility, rheological properties of CC solution and the properties of regenerated membranes of CC were studied. FTIR and ~ (13) C-NMR measurements showed that CC; was successfully synthesized in DMAC system. In this system, the optimum conditions for the preparation of CC are as follows: reaction temperature is 160 鈩，
本文编号：2438062
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