【摘要】：纖維素被認為是目前為止最有潛力替代化石能源的天然高分子;廣泛應用于食品、能源、材料等行業(yè)。纖維素內(nèi)部存在發(fā)達的氫鍵網(wǎng)絡,使得纖維素很難被溶解和熔融,使纖維素在加工和應用方面受到了限制。為了能夠使纖維素溶解在一般溶劑中,并探索出一條低成本、綠色、環(huán)保的工藝路線;本研究中,使用廉價、高沸點、非質(zhì)子、極性溶劑N,N-二甲基乙酰胺(DMAC)為介質(zhì),以纖維素和尿素為原料,通過酯化反應制備了纖維素氨基甲酸酯(CC),采用傅里葉變換紅外光譜儀(FTIR)、X-射線衍射儀(XRD)、~(13)C-核磁共振儀(~(13)C-NMR)、熱重分析儀(TG)、掃描電子顯微鏡(SEM)和偏光顯微鏡等儀器對產(chǎn)物進行性能表征;對CC的制備條件、溶解性能、CC溶液的流變性能以及其再生膜的性能進行了研究。FTIR和~(13)C-NMR測試表明,在DMAC體系中,成功合成了 CC;在該體系中,制備CC的最佳條件為:反應溫度為160℃,反應時間為6h,堿纖維素、尿素和DMAC的最佳質(zhì)量比為1:4:16。XRD測試結(jié)果表明,在DMAC體系中酯化前后,纖維素的晶型沒有發(fā)生變化,結(jié)晶度略有降低;通過稀H2SO4凝固浴再生后得到的纖維素再生膜,膜的晶型和堿纖維素的晶型一樣屬于纖維素Ⅱ晶型結(jié)構(gòu),而再生膜的結(jié)晶度有所降低。TG測試表明,酯化后纖維素的熱穩(wěn)定性略有降低;再生過程中,纖維素再生膜的結(jié)晶度有所降低,由于再生膜中存在的金屬陽離子Na+能夠催化氧化纖維素,使得纖維素再生膜的熱穩(wěn)定降低。流變測試表明,CC溶液為假塑性流體,隨著溫度的升高,溶液的粘度先降低再升高;在相同的剪切速率下,CC質(zhì)量分數(shù)越高的溶液,其粘度越大,凝膠溫度越低,溶液越不穩(wěn)定。SEM測試結(jié)果表明,在DMAC的作用下,通過纖維素酯化反應,纖維素表面的結(jié)構(gòu)遭到破壞,表面裂紋增加,變得粗糙,略有剝落。對于纖維素再生膜,用質(zhì)量分數(shù)越低的稀H2SO4凝固浴制備的纖維素再生膜,其表面更加粗糙,表面孔更多,用質(zhì)量分數(shù)越高的稀H2SO4凝固浴制備的纖維素再生膜,其表面更加致密。纖維素再生膜的過濾性能測試表明,膜的純水通量隨著壓力的增加而增加,隨著凝固浴中H2SO4的質(zhì)量分數(shù)的增加而降低。用質(zhì)量分數(shù)為5%的稀H2SO4凝固浴制備的纖維素再生膜對亞甲基藍的截留率高達97.5%。因而纖維素再生膜在印染廢水處理方面有很好的應用前景。
[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，

本文編號：2438062