【作者】 万超；

【导师】 高山俊；

【作者基本信息】 武汉理工大学 ， 材料加工， 2010， 硕士

【摘要】 随着合成高分子材料对环境所造成的白色污染越来越严重,石油资源日益缺乏,导致石油价格的持续上涨,使得人们对可降解的、价格便宜的再生资源的研究开发越来越重视。天然多糖由于其普遍存在于大自然中来源广泛,并具有可生物降解、可再生、无毒等优异性能,因而受到人们的普遍关注。但天然多糖本身结构中含有大量羟基和一些其他极性基团,易形成分子内和分子间的氢键,导致天然多糖本身难以溶解和熔融,因此其应用受到了一定的限制,目前研究和开发天然多糖的有效溶剂已经引起了人们的广泛关注。在本文的研究工作中,首先,合成离子液体AMIMCl,通过核磁共振对其进行结构分析证实所合成产物正确。通过偏光显微镜观测黄原胶、瓜尔胶、卡拉胶和魔芋多糖这四种多糖在离子液体中的溶解过程表明,所选四种多糖均能够较好的溶解在所合成的离子液体中,利用红外、XRD光谱对溶解前后的多糖结构的进行分析,结果表明离子液体AMIMCl为所测四种多糖的有效真溶剂,但溶解过程中离子液体对多糖结构上的氢键有一定的破坏作用,再生后多糖的结晶度也有部分下降。对再生前后魔芋多糖进行DSC和TG分析可知,再生后魔芋多糖的热分解温度和热稳定性均有所下降。其次,对魔芋多糖在离子液体AMIMCl中进行均相乙酰化改性。通过红外和核磁图谱分析反应前后魔芋多糖的结构,结果表明魔芋多糖在离子液体中的均相乙酰化反应成功进行。探讨反应条件对取代度的影响,发现在无催化剂,反应时间为0.75h,温度为80℃,乙酸酐与魔芋中羟基的摩尔比为6：1的条件下,可达到最高取代度2.15。对原始魔芋和所得不同取代度的乙酰化魔芋进行溶解性能测试,发现原始魔芋多糖在DMF、DMSO、THF中均不能溶解,通过改性后的魔芋多糖在取代度达到1.02后便可溶解于DMSO,取代度达1.42后可溶于DMF,取代度达2.01时可溶于THF,并且随着取代度的提高溶解过程越来越容易。最后,在以NaOH为活化剂的条件下,通过苯甲酰氯对魔芋多糖进行苯甲酰化改性,引入苯甲酰基以增强魔芋分子链的刚性,对反应前后的魔芋多糖进行红外和核磁图谱表征分析,证明苯甲酰化反应成功进行,并测得产物的取代度为2.45。将苯甲酰化的魔芋多糖按照不同的浓度比例分别溶解在离子液子AMIMCL中,通过POM和阿贝尔折射仪观测表明,溶液出现液晶相的临界浓度为16wt%。利用流变仪对不同溶度的溶液进行流变性能测试,通过稳态流变测试探讨浓度和剪切速率对溶液稳态粘度的影响,并通过动态频率扫描测试浓度和频率对溶液储能模量和损耗模量的影响。更多还原

【Abstract】 Now the problem of white pollution caused by the synthetic polymer materials becomes more and more serious, and the oil prices continue to rise for the petroleum resources are being exhausted gradually. Therefor people begin to play more and more attention in reasearching and exploitation of biodegradable and renewable resource. Natural polysaccharide for it plentiful and widely existed in nature has got people’s attention. And compares to the the synthetic polymer materials, the natural polysaccharide has many advantages such as biodegradable, renewable and non-toxic. But for their stiff molecules and close chain packing via numerous inter-molecular and intramolecular hydrogen bonds, it is extremely difficult to dissolve in most common organic solvents, so the application of natural polysaccharide has been restricted in a certain extent. Now reasearching and exploitation of the real solvent of natural polysaccharide has aroused more and more people’s attention.In the present study, firstly we synthesized the ionic liquid AMIMCl according to the previous article, and used 1H-NMR to confirm the product is the right product. Through the POM to observe the dissolution process of Xanthan gum, guar gum, Carrageenan and KGM respectively, and it proved all the polysaccharides can dissolve in AMIMCl. The structure and crystal type of the polysaccharide before and after regeneration has been characterized by FTIR and XRD. The result shows that the ionic liquid AMIMCl is the real solvent of these polysaccharides, but the structure has been a little destroyed in the process of dissolution. Used DSC and TG to research the thermal property of the KGM before and after regeneration, and found that both the decomposition temperature and the thermal stability had a little decline.Secondly, the homogenous acetylation of KGM in AMIMCl has been accomplished in our laboratory. Through FTIR,1H-NRM and 13C-NRM to analyse the structure of KGM before and after reaction, and found out that the reaction has taken place successfully. When the reaction time is 0.75h, temperature is 80℃and the the molar ratio of acetic anhydride/hydroxyl group is 6:1, the DS could reach to 2.15 in the absence of any catalysts. The solubility of the native KGM and the products with different DS in the three solvents, DMF, DMSO and THF, was aslo been studied, and found out that the DS has a great influence in the solubility.Finally, the benzoyl KGM was synthesised to improve the chain rigidity of KGM. The structure of the native KGM and the benzoyl KGM were investigated by FTIR and 1H-NRM and 13C-NRM, it is indicated that the benzoyl KGM was synthesised successfully and the DS was measured to be 2.45. A series of benzoyl KGM/AMIMCl solutions with various concentrations were prepared, and the liquid crystal phase could be obsevered after the concentration to be 16wt%through the POM and refractive index. The steay viscosity and dynamic rheological properties of the benzoyl KGM/AMIMCl solutions with various concentrations were tested through the rheology measurements.更多还原