發(fā)布時(shí)間：2018-04-21 16:00

  本文選題：可生物降解泡沫材料 + 納米原纖化纖維素��； 參考：《陜西科技大學(xué)》2017年碩士論文

【摘要】：隨著環(huán)境污染問(wèn)題的日益嚴(yán)重和石油資源的枯竭,研究開發(fā)可生物降解、資源豐富、可回收利用的新型泡沫緩沖材料替代傳統(tǒng)泡沫塑料已成為社會(huì)上亟需解決的重大問(wèn)題。目前,納米纖維素基泡沫材料被認(rèn)為是極具開發(fā)前景的可生物降解泡沫材料之一,研究其制備工藝與微觀泡孔結(jié)構(gòu)及性能的關(guān)系,開發(fā)泡孔結(jié)構(gòu)調(diào)控技術(shù),對(duì)獲取不同結(jié)構(gòu)和應(yīng)用性能的納米纖維素基緩沖材料具有重要的意義。因此,本文重點(diǎn)研究了納米纖維素基泡沫材料泡孔結(jié)構(gòu)的調(diào)控技術(shù),主要內(nèi)容如下:首先,對(duì)納米原纖化纖維素(NFC)的物化特性進(jìn)行表征。在此基礎(chǔ)上,通過(guò)改變NFC濃度和冷凍溫度對(duì)NFC泡沫材料的泡孔結(jié)構(gòu)進(jìn)行調(diào)控。NFC濃度增大使其泡孔分布變均勻,孔徑尺寸減小,但局部會(huì)出現(xiàn)大孔或致密結(jié)構(gòu);低溫冷凍使泡孔分布變得更加均勻,孔徑尺寸減小。其次,采用醇類有機(jī)溶劑對(duì)NFC泡沫材料的結(jié)構(gòu)進(jìn)行調(diào)控。研究發(fā)現(xiàn):添加乙醇、異丙醇和正丁醇后泡沫材料的泡孔結(jié)構(gòu)近似于蜂窩多孔材料,泡孔排列有規(guī)則,分布均勻且呈層狀結(jié)構(gòu),但孔徑尺寸較大;添加甲醇后孔徑尺寸變均勻,但泡孔分布雜亂無(wú)章;添加叔丁醇后泡孔分布均勻,孔徑尺寸較小,但形狀無(wú)規(guī)則。此外,添加有機(jī)溶劑后泡沫材料的密度減小,孔隙率增加,收縮率減小,但導(dǎo)熱系數(shù)和熱穩(wěn)定性基本沒(méi)有變化。綜合分析確定乙醇的調(diào)控效果最佳。然后,研究了乙醇濃度、冷凍溫度和NFC濃度對(duì)NFC泡沫材料結(jié)構(gòu)與性能的影響。乙醇濃度增大使泡沫材料的泡孔分布和孔徑尺寸變均勻,形狀趨于圓形;冷凍溫度降低和NFC濃度增加使泡孔呈現(xiàn)層狀結(jié)構(gòu)排列,層與層之間出現(xiàn)柱狀纖維結(jié)構(gòu),泡孔分布變均勻,形狀趨于矩形;但冷凍溫度較低,NFC濃度較高時(shí),層狀結(jié)構(gòu)和柱狀結(jié)構(gòu)消失,孔徑尺寸減小。最佳制備工藝為:乙醇濃度為5wt%,NFC濃度為3wt%,冷凍溫度為-55℃。此條件下,泡沫材料的平均孔面積為3231.44μm2,平均孔壁厚度為2.46μm,泡孔密度為4.89×106個(gè)/cm3;密度為35.90kg/m3,孔隙率為97.66%,導(dǎo)熱系數(shù)為0.0384W/(m·K)。最后,探討了支鏈淀粉含量、冷凍溫度和固含量對(duì)NFC基復(fù)合泡沫材料結(jié)構(gòu)與性能的影響。隨著支鏈淀粉含量的增加,泡沫材料的泡孔分布變均勻,孔徑尺寸增大,出現(xiàn)孔壁結(jié)構(gòu),但含量超過(guò)70%時(shí),泡孔尺寸變小且分布不均勻。固含量增加使泡孔形狀變得不規(guī)則,分布不均勻,孔徑尺寸減小。冷凍溫度的降低使泡孔分布變均勻,泡孔大小變小,出現(xiàn)閉孔結(jié)構(gòu),但孔壁較薄,強(qiáng)度提高較少。支鏈淀粉與NFC混合均勻后可形成類似“鋼筋混凝土”結(jié)構(gòu),使支鏈淀粉/NFC復(fù)合泡沫材料的強(qiáng)度提高。最佳制備工藝為:支鏈淀粉含量為30%,固含量為3wt%,冷凍溫度為-55℃。此條件下,泡沫材料的平均孔面積為195.99μm2,平均孔壁厚度為1.04μm,泡孔密度為4.68×108個(gè)/cm3;楊氏模量為713.14KPa,屈服強(qiáng)度為92.28KPa,能量吸收值為13.24kJ/m3。綜上,通過(guò)調(diào)節(jié)NFC濃度和冷凍溫度,以及醇類有機(jī)相介入和支鏈淀粉增強(qiáng)等技術(shù)手段,可實(shí)現(xiàn)納米纖維素基泡沫材料泡孔結(jié)構(gòu)的有效調(diào)控。原料資源豐富、工藝過(guò)程清潔,為制備高性能、可生物降解的納米纖維素基復(fù)合泡沫材料提供了可能。
[Abstract]:With the increasingly serious environmental pollution problems and the depletion of oil resources, the research and development of biodegradable and rich resources, the new foam cushioning materials can be recycled to replace the traditional foam plastics have become a major problem to be solved in society. At present, nanoscale foam foam material is considered to be a very promising biodegradable material. One of the foam materials is to study the relationship between the preparation technology and the microstructure and properties of the microbubbles. The development of the regulation technology of the pore structure is of great significance for obtaining the nanofibric buffer materials with different structures and application properties. Therefore, the main research on the regulation technology of the pore structure of nanofibrous foam materials is mainly studied. The contents are as follows: first, the physicochemical properties of nano fibrinolytic cellulose (NFC) are characterized. On this basis, the bubble pore structure of NFC foam is regulated by changing the concentration of NFC and the freezing temperature. The pore size of the foam is more uniform and the size of the pore size decreases, but there will be large pore or compact structure in the local area; cryopreservation makes the bubble. The pore size distribution becomes more uniform and the size of the pore size decreases. Secondly, the structure of NFC foam is regulated by alcohols organic solvents. It is found that the bubble pore structure of the foam materials with ethanol, isopropanol and n-butanol is similar to the honeycomb porous material, and the bubble holes are arranged regularly, distributed uniformly and layered, but the size of the pore size is larger. After the addition of methanol, the size of the pore is disorderly, and the pore size distribution is uniform and the size is smaller after adding TERT butanol, but the shape of the pore is irregular. In addition, the density of the foam material decreases, the porosity increases and the shrinkage decreases, but the thermal conductivity and thermal stability are basically unchanged. The effect of alcohol is the best. Then, the effects of ethanol concentration, freezing temperature and NFC concentration on the structure and properties of NFC foam materials are studied. The increase of ethanol concentration makes the bubble pore distribution and aperture size become uniform, the shape tends to round, and the freezing temperature decreases and the concentration of NFC increases the layer structure arrangement, between the layer and the layer. There is a columnar fiber structure, the distribution of the bubble holes becomes uniform and the shape tends to be rectangular, but the freezing temperature is low. When the concentration of NFC is high, the layer structure and columnar structure disappear and the size of the pore size decreases. The optimum preparation process is as follows: the concentration of ethanol is 5wt%, the concentration of NFC is 3wt%, and the freezing temperature is -55. The average thickness of the pore wall is 2.46 mu m, the density of the bubble hole is 4.89 x 106 /cm3, the density is 35.90kg/m3, the porosity is 97.66%, the thermal conductivity is 0.0384W/ (M. K). Finally, the effect of the amylopectin content, the freezing temperature and the solid content on the structure and properties of the NFC based composite foam material is discussed. If the content is over 70%, the size of the bubble hole becomes smaller and the distribution is uneven. The increase of the solid content makes the shape of the hole become irregular, the distribution is uneven, the size of the pore size decreases. The reduction of the freezing temperature makes the distribution of the hole even, the size of the bubble hole becomes smaller and the structure of the hole is smaller, but the wall of the hole is thinner and the strength is stronger. Less improvement. The mix of amylopectin and NFC can form a similar "reinforced concrete" structure to improve the strength of the amylopectin /NFC composite foam material. The optimum preparation process is: the amylopectin content is 30%, the solid content is 3wt%, the freezing temperature is -55 C. Under this condition, the average pore area of the foam material is 195.99 Mu m2, and the average pore wall is the pore wall. The thickness is 1.04 mu m, the density of the bubble hole is 4.68 x 108 /cm3, the young's modulus is 713.14KPa, the yield strength is 92.28KPa, the energy absorption value is 13.24kJ/m3., and the effective modulation of the pore structure of the nanoscale foam material can be realized by adjusting the NFC concentration and freezing temperature, as well as the alcohols organic phase intervention and the amylopectin enhancement and so on. Raw materials are rich in resources and clean in process. It is possible to prepare high-performance, biodegradable nano cellulose based composite foam materials.

【學(xué)位授予單位】：陜西科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ328

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