本文選題：納米纖維素 + 醇凝膠�。� 參考：《南京林業(yè)大學(xué)》2017年碩士論文

【摘要】：氣凝膠作為一種新型材料,具有很多優(yōu)良的性能,如高比表面積、高孔隙率、低密度、低導(dǎo)熱系數(shù)、低介電常數(shù)、低光折射率、極強(qiáng)的氣體吸附能力等,已被列為十大熱門材料之一。目前氣凝膠的研究多集中在有機(jī)、無(wú)機(jī)和有機(jī)-無(wú)機(jī)復(fù)合氣凝膠。纖維素氣凝膠作為新生的第三代氣凝膠材料,不僅具備了傳統(tǒng)氣凝膠的優(yōu)良性能,同時(shí)還融入了纖維素的一些優(yōu)異性能,如原料充足、可降解、可再生、生物相容性好等,使其具有廣闊的應(yīng)用前景。本論文以紙漿為原料,分別采用硫酸水解法和過(guò)硫酸銨氧化法制備納米纖維素納米晶須(Cellulose Nanocrystalline(CNC))和納米纖維(Cellulose Nanofiber(CNF)),并對(duì)兩種納米纖維素性能進(jìn)行分析和表征;分別以納米纖維素納米晶須和納米纖維為原料,采用無(wú)機(jī)鹽凝膠法制備水凝膠,通過(guò)溶劑置換得到醇凝膠,最后利用超臨界干燥和冷凍干燥制備出球形氣凝膠,探討兩種納米纖維素醇凝膠的最佳超臨界干燥工藝,并對(duì)氣凝膠的性能進(jìn)行分析和表征。具體結(jié)論如下所示:1)兩種納米纖維素依然保持纖維素Ⅰ型結(jié)構(gòu),結(jié)晶度增加,熱穩(wěn)定性降低。納米纖維素納米晶須的結(jié)晶度為75.4%,熱降解初始溫度(T_0)和最大失重率溫度(T_(max))分別為200℃和265℃,直徑主要分布在24-35nm范圍內(nèi),長(zhǎng)度在250-400nm之間,表面引入磺酸基團(tuán),為兩端尖的短棒狀結(jié)構(gòu);納米纖維的結(jié)晶度為68.9%,熱降解初始溫度(T_0)和最大失重率溫度(T_(max))分別為210℃和344℃,直徑主要分布在50-70nm之間,長(zhǎng)度為1-2微米,表面部分羥基被氧化成了醛基和羧基,為長(zhǎng)纖維狀。與納米纖維素納米晶須相比,納米纖維的熱降解初始溫度和最大失重率溫度較高,直徑和長(zhǎng)度較大,但結(jié)晶度較低,兩種納米纖維素的形狀也不同。這些差異主要因?yàn)橹苽浞椒ǖ牟煌鶎?dǎo)致。2)質(zhì)量分?jǐn)?shù)為1.5%的CNC醇凝膠最佳超臨界CO_2干燥工藝為:45℃、2h、12MPa,質(zhì)量分?jǐn)?shù)為2.5%和3.5%的CNC醇凝膠最佳超臨界CO_2干燥干工藝為:45℃、3h、12MPa;質(zhì)量分?jǐn)?shù)為1.5%的CNF醇凝膠最佳超臨界CO_2干燥工藝為:50℃、4h、13MPa,質(zhì)量分?jǐn)?shù)為2.5%和3.5%的CNF醇凝膠最佳超臨界CO_2干燥工藝為:50℃、2h、13MPa。3)采用萬(wàn)能力學(xué)實(shí)驗(yàn)機(jī)測(cè)定其力學(xué)性能:超臨界CO_2干燥后的質(zhì)量分?jǐn)?shù)分別為1.5%、2.5%、3.5%的CNC氣凝膠和CNF氣凝膠,其壓縮強(qiáng)度分別為0.32MPa、0.40MPa、0.46MPa和0.37MPa、0.67MPa、0.77MPa;經(jīng)液氮冷凍干燥得到的質(zhì)量分?jǐn)?shù)分別為1.5%、2.5%、3.5%的CNF氣凝膠,其壓縮強(qiáng)度分別為0.85、1.32,和1.47MPa。納米纖維素氣凝膠的壓縮強(qiáng)度隨著納米纖維素質(zhì)量分?jǐn)?shù)的增加而增加。4)利用掃描電子顯微鏡(Sweep Electron Microscope簡(jiǎn)稱SEM)對(duì)其內(nèi)部微觀形貌進(jìn)行觀察:超臨界CO_2干燥得到的氣凝膠內(nèi)部為三維網(wǎng)絡(luò)結(jié)構(gòu),冷凍干燥得到的氣凝膠內(nèi)部為三維層狀結(jié)構(gòu),且納米纖維素質(zhì)量分?jǐn)?shù)越高,內(nèi)部結(jié)構(gòu)越密實(shí)。5)通過(guò)比表面積分析儀對(duì)納米纖維素氣凝膠的吸附量和孔徑分布進(jìn)行分析:納米纖維素氣凝膠的N_2等溫吸附線均符合第Ⅱ類等溫吸附線,以多層吸附為主,孔徑主要以介孔為主。隨著納米纖維素質(zhì)量分?jǐn)?shù)的增加,吸附量增加,孔徑減小。6)當(dāng)納米纖維素質(zhì)量分?jǐn)?shù)相同時(shí),CNC氣凝膠的干燥收縮率、內(nèi)部孔徑大于CNF氣凝膠,其壓縮強(qiáng)度、比表面積比CNF氣凝膠小;通過(guò)冷凍干燥得到的纖維素氣凝膠的密度、壓縮強(qiáng)度和收縮率比超臨界CO_2干燥得到的氣凝膠大,但比表面積和內(nèi)部孔徑小于超臨界CO_2干燥得到的氣凝膠;隨著納米纖維素質(zhì)量分?jǐn)?shù)的增加,醇凝膠的干燥收縮率降低,氣凝膠的密度升高
[Abstract]:As a new material, aerogels have many excellent properties, such as high surface area, high porosity, low density, low thermal conductivity, low dielectric constant, low refractive index, and very strong gas adsorption capacity. The aerogels have been listed as one of the ten most popular materials. As a new third generation aerogel, gelatin. Not only has the excellent performance of the traditional aerogels, but also integrates some excellent properties of cellulose, such as sufficient raw material, biodegradability, renewable, good biocompatibility and so on, so that it has a broad application prospect. This paper uses pulp as raw material, using sulphuric acid water respectively. Nanofibric nanofibers (Cellulose Nanocrystalline (CNC)) and nanofibers (Cellulose Nanofiber (CNF)) were prepared by solution and ammonium persulfate oxidation. The properties of two kinds of nanofibers were analyzed and characterized. Hydrogels were prepared by nanosilet nanofibers and nanofibers respectively by inorganic salt gel method. The spherical aerogels were prepared by supercritical drying and freeze-drying. The optimal supercritical drying process of two nanosilet gels was investigated and the properties of aerogels were analyzed and characterized. The specific conclusions are as follows: 1) two nanosilics still maintain the structure and crystallinity of cellulose type I. The crystallinity of nanoscale nanofibers was 75.4%, the initial temperature of thermal degradation (T_0) and the maximum weightlessness temperature (T_ (max)) were 200 and 265 C respectively. The diameter of nanofibric nanofibers was mainly in the 24-35nm range, the length was between 250-400nm and the surface was introduced into the short rod like structure at both ends, and the crystallization of nanofibers. The initial thermal degradation temperature (T_0) and the maximum weight loss temperature (T_ (max)) are 210 and 344 C respectively, the diameter is mainly between 50-70nm, the length is 1-2 micron, the surface hydroxyl group is oxidized to aldehyde group and carboxyl group, and it is long fiber. Compared with nanofiber nanofibers, the initial temperature and maximum thermal degradation temperature of nanofibers are compared with nanofibers. The weight loss rate is higher, the diameter and the length are larger, but the crystallinity is low, and the shape of the two kinds of nanoscale is different. The difference is mainly due to the best supercritical CO_2 drying process of the CNC alcohol gel with the mass fraction of.2) with the mass fraction of 1.5%, which is 45, 2h, 12MPa, the CNC alcohol gel with the mass fraction of 3.5% and the optimum overcoming of the gel. The dry drying process of boundary CO_2 is: 45 C, 3h, 12MPa; the optimum supercritical CO_2 drying process of CNF alcohol gel with a mass fraction of 1.5% is: 50 C, 4h, 13MPa, the optimum supercritical CO_2 drying process of CNF alcohol gel 2.5% and 3.5%: 50 C, 2h, 13MPa.3) using the universal mechanical test machine to determine its mechanical properties: the quality after supercritical CO_2 drying The compression strength of CNC aerogels and CNF aerogels of 1.5%, 2.5%, 3.5%, respectively, 0.32MPa, 0.40MPa, 0.46MPa and 0.37MPa, 0.67MPa, 0.77MPa, and CNF aerogels of 1.5%, 2.5%, 3.5%, respectively by liquid nitrogen freeze drying, are divided into 0.85,1.32 and compressive strength of 1.47MPa. nanoscale aerogels. With the increase of the mass fraction of nanoscale cellulose (.4), the internal micromorphology was observed by scanning electron microscope (Sweep Electron Microscope for short). The internal microstructure of the aerogel obtained by supercritical CO_2 drying was three-dimensional network structure, and the interior of the aerogel obtained by freeze-drying was three-dimensional and nanofiber quality. The adsorption capacity and pore size distribution of nano cellulose aerogels are analyzed by the surface area analyzer (.5). The N_2 isothermal adsorption line of nanoshogel aerogels conforms to class II isothermal adsorption line, and the main pore size is mesoporous. With the mass fraction of nanoscale. When the mass fraction of nanoscale is the same, the drying shrinkage of CNC aerogels is larger than that of CNF aerogels when the mass fraction of nanoscale is the same. The compressive strength and specific surface area of the aerogels are smaller than that of the CNF aerogels, and the density, compression strength and shrinkage rate of the cellulose aerogels obtained by freeze-drying are obtained than that of the supercritical CO_2 dry CO_2. Aerogels are larger, but the specific surface area and inner pore size are less than the aerogels obtained by supercritical CO_2 drying. With the increase of the mass fraction of nanoscale, the drying shrinkage of the alcohol gel decreases and the aerogel density increases.
【學(xué)位授予單位】：南京林業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ352.79;TQ427.26

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 王曉宇;張洋;江華;王超;宋宇軒;周兆兵;;氧化降解法制備納米纖維素的特性分析[J];西北林學(xué)院學(xué)報(bào);2016年04期

2 馬書(shū)榮;米勤勇;余堅(jiān);何嘉松;張軍;;基于纖維素的氣凝膠材料[J];化學(xué)進(jìn)展;2014年05期

3 王寶和;李群;;氣凝膠制備的干燥技術(shù)[J];干燥技術(shù)與設(shè)備;2013年04期

4 何文;張齊生;蔣身學(xué);孫豐文;;慈竹納米纖維素的制備及特征分析[J];林業(yè)科技開(kāi)發(fā);2013年04期

5 何文;尤駿;蔣身學(xué);張齊生;;毛竹納米纖維素晶體的制備及特征分析[J];南京林業(yè)大學(xué)學(xué)報(bào)(自然科學(xué)版);2013年04期

6 藺燾;郭文靜;方露;王正;;3種方法計(jì)算棉稈纖維素結(jié)晶度的比較分析[J];東北林業(yè)大學(xué)學(xué)報(bào);2013年02期

7 李媛媛;戴紅旗;;化學(xué)法制備納米微晶纖維素的研究進(jìn)展[J];南京林業(yè)大學(xué)學(xué)報(bào)(自然科學(xué)版);2012年05期

8 王芹芳;劉魏;;纖維素在離子液體中反應(yīng)的研究進(jìn)展[J];河北化工;2012年02期

9 呂玉霞;李小艷;米勤勇;王德修;余堅(jiān);張軍;;以纖維素/AmimCl溶液制備纖維素氣凝膠[J];中國(guó)科學(xué):化學(xué);2011年08期

10 陶丹丹;白繪宇;劉石林;劉曉亞;;纖維素氣凝膠材料的研究進(jìn)展[J];纖維素科學(xué)與技術(shù);2011年02期

相關(guān)會(huì)議論文 前1條

1 鄭賢德;林秀誠(chéng);趙鶴皋;;中國(guó)冷凍干燥技術(shù)進(jìn)展[A];第七屆全國(guó)冷凍干燥學(xué)術(shù)交流會(huì)論文集[C];2002年

相關(guān)博士學(xué)位論文 前2條

1 李文定;納米結(jié)晶纖維素改性三聚氰胺樹(shù)脂及其復(fù)合材料的特性研究[D];南京林業(yè)大學(xué);2015年

2 左建國(guó);叔丁醇/水共溶劑的熱分析及其冷凍干燥研究[D];上海理工大學(xué);2005年

相關(guān)碩士學(xué)位論文 前1條

1 趙路陽(yáng);二乙烯基三胺基氧化纖維素的合成及對(duì)尿素、砷（Ⅲ）的雙機(jī)制吸附研究[D];黑龍江大學(xué);2010年

，

本文編號(hào)：2026013