本文選題：納米纖維素　切入點(diǎn)：氣凝膠　出處：《青島科技大學(xué)》2017年碩士論文

【摘要】：納米纖維素作為一種納米尺度的纖維素聚集體,具有高結(jié)晶度、高楊氏模量、高強(qiáng)度等特性,同時(shí)還具有良好的生物相容性、可降解、無毒以及可再生等特點(diǎn)。納米纖維素作為一種綠色的增強(qiáng)材料受到越來越多的關(guān)注,在制備高性能納米復(fù)合材料中具有巨大的應(yīng)用前景。納米纖維素表面存在大量的羥基,能夠形成強(qiáng)氫鍵作用,同時(shí)表面存在的羥基使其易于化學(xué)改性。本文采用物理法制備了納米纖維素纖絲(NCFs),采用化學(xué)法制備了納米纖維素晶體(CNCs)。以NCFs為原料制備了氣凝膠,以CNCs為填料提高了雙組份水性聚氨酯(2K-WPU)和室溫硫化硅橡膠(RTV)的性能。以NCFs為原料,使其在四氯化錫的催化下與1,4-丁二醇二縮水甘油醚(BDGE)發(fā)生交聯(lián)反應(yīng)而制備了多孔的納米纖維素氣凝膠。制備的納米纖維素氣凝膠具有連續(xù)的多孔網(wǎng)絡(luò)結(jié)構(gòu),仍保持纖維素I型結(jié)構(gòu),初始分解溫度在300℃以上。BDGE的添加量為NCFs質(zhì)量的2倍時(shí),制備的氣凝膠密度為0.0202mg/cm3,吸水倍數(shù)為36 g·g-1,氣凝膠在水和DMSO中能恢復(fù)形變的90%以上,重復(fù)使用5次,吸水倍數(shù)仍高達(dá)30 g·g-1。以CNCs為填料提高雙組份水性聚氨酯(2K-WPU)的性能,考察了2K-WPU/CNCs納米復(fù)合材料的形貌結(jié)構(gòu)、熱力學(xué)性能和機(jī)械性能。結(jié)果表明CNCs與2K-WPU相容性好且CNCs在聚合物基質(zhì)中均勻分散。CNCs作為填料顯著的提高了2K-WPU的拉伸強(qiáng)度,隨著CNCs含量由0%增加至9%,2K-WPU/CNCs復(fù)合材料的拉伸強(qiáng)度由2.63 MPa增加至10.22 MPa,提高了288.6%,斷裂伸長率由644.3%下降至87.2%。隨著CNCs用量的增加,熱穩(wěn)定性和玻璃化轉(zhuǎn)變溫度也有所上升。此外,本文還利用氨基甲酸酯化反應(yīng)對(duì)CNCs的表面進(jìn)行功能化改性,采用3-異氰酸酯基丙基三甲氧基硅烷提高CNCs在RTV基質(zhì)中的分散性,制備的硅氧烷化納米纖維素晶體(SCNCs)與商業(yè)硅橡膠0混合均勻后室溫硫化。SCNCs對(duì)RTV具有較強(qiáng)的增強(qiáng)作用,僅添加質(zhì)量分?jǐn)?shù)3%的SCNCs,納米復(fù)合材料的拉伸強(qiáng)度由0.46 MPa上升至1.45 MPa,提高了215.2%,斷裂伸長率由493.4%下降至444.0%,下降了9.9%。隨著SCNCs含量的增加,熱穩(wěn)定性明顯提高。
[Abstract]:As a kind of nano-scale cellulose aggregates, nano-cellulose has the characteristics of high crystallinity, high Young's modulus and high strength, and also has good biocompatibility and biodegradability. As a green reinforcing material, nano-cellulose has attracted more and more attention, and has a great application prospect in the preparation of high-performance nanocomposites. There are a lot of hydroxyl groups on the surface of nano-cellulose. In this paper, nanocellulose fibers were prepared by physical method, nanocellulose crystals were prepared by chemical method, aerogels were prepared using NCFs as raw material. The properties of two-component waterborne polyurethane 2K-WPUand room temperature vulcanized silicone rubber were improved by using CNCs as filler. NCFs was used as raw material. The porous nano-cellulose aerogels were prepared by the crosslinking reaction of stannous tetrachloride with 1,4-butanediol diglycidyl ether BDGE.The prepared nanocellulose aerogels have continuous porous network structure. When the initial decomposition temperature is above 300 鈩，

本文編號(hào)：1688383