氧化淀粉的接枝改性及其电流变性能研究

【作者】 刘雪晴；

【导师】 张明；

【作者基本信息】 扬州大学 ， 物理化学， 2006， 硕士

【摘要】 淀粉是一种廉价的天然可再生资源,具有极好的生物降解性能和再生性能,是一种理想的绿色环保材料。其分子的基本结构为葡萄糖单元,每个葡萄糖单元的2、3、6位C上各有一个活性羟基,可通过羟基的酯化、醚化、氧化、交联、接枝共聚等化学改性,合成变性淀粉。氧化淀粉是淀粉在酸、碱、中性介质中与氧化剂作用而生成的产品。淀粉经氧化后减少了分子中羟基的数量,使分子的缔合受阻,减弱了分子间氢键的结合能力;同时降低了聚合度,增加了淀粉的水溶性、粘结力和稳定性。接枝淀粉是天然高分子化合物与合成聚合物用化学键彼此连接而成的一种接枝共聚物,既具有天然高分子性质又具有合成高分子性质。接枝淀粉提高了天然高分子的使用价值,扩大了其应用范围,这是淀粉改性研究比较活跃的领域之一。本文以淀粉为原料,首先确定合成氧化淀粉的最佳条件,在此基础上对氧化淀粉进行接枝共聚得到一种新型的复合变性淀粉,最后在淀粉接枝共聚物上引入稀土元素,增加其极化能力,合成具有一定生物降解性能的电流变材料。1.氧化淀粉的合成与表征选用H₂O₂作为氧化剂,FeSO₄作为催化剂合成了氧化淀粉。利用红外光谱、X-射线粉末衍射和扫描电镜等手段对氧化淀粉进行了表征,并利用热糊滴定法测定了氧化淀粉中的羧基含量,羟胺法测定了氧化淀粉中的羰基含量,讨论了H₂O₂用量、溶液pH对淀粉氧化程度的影响,结果表明:用H₂O₂-FeSO₄氧化还原体系氧化时对淀粉的晶型结构破坏很小,氧化反应主要发生在淀粉的非结晶区,只有少量发生在结晶区;淀粉30g,H₂O70ml,H₂O₂用量为3.5ml,溶液pH为9时对淀粉的氧化程度最大,羧基、羰基含量最大。2.淀粉及氧化淀粉接枝共聚反应的研究选用（NH₄）₂S₂O₈-Na₂S₂O₃引发体系,通过自由基接枝共聚的方法,在淀粉大分子链上引入丙烯酸丁脂。采用红外光谱、同步热分析、扫描电镜等对接枝产物进行了结构表征,测定了单体用量、引发剂用量以及反应温度对接枝率和接枝效更多还原

【Abstract】 Starch is a cheap, natural, renewable resource. It is an ideal“Green”material, presenting excellent biodegradability and regenerability. The basic molecular structure of starch is anhydroglulose unit, and the carbon of 2, 3, 6 bits of every anhydroglulose unit has a bioactive hydroxyl group. Therefore, chemical modification, such as oxidation, esterification, etherification, cross linking, and graft copolymerization of hydroxyl group can be carried out on starch to change its reactive properties.Oxidized starch is synthesized by starch and oxidant under acide, alkali or neutral medium. After oxidation, the amount of hydroxyl decreases, the assciation of molecules is blocked off, and the binding level of hydrogen bonds amoung molecules reduces. Meanwhile, polymerization degree of starch reduces, while the water- solubility, felt force and stability increase.The starch graft copolymer, one of the active research fields in starch modification, is a kind of copolymer bonded natural polymer and synthesized polymer. It shows excellent properties both of these two polymers, extending the application range of natural polymer.In this paper, starch was used as raw material. Firstly, optimal condition of synthesis oxidized starch was ascertained, and then the modified starch composite was prepared by oxidized starch from graft copolymerization. Finally, rare earth element was introduced into starch graft copolymer. The polarization ability was improved, and electrorheological fluid with biodegradability was synthesized.1. Synthesis and characterization of oxidized starchOxidized starch was synthesized by using H₂O₂ as oxidant, and FeSO₄ as catalyst. Oxidized starch was characterized by IR, XRD and SEM. The content of carboxyl group was tested by hot paste titration, and the content of carbonyl group was decided by hydroxylamine method. The dosage of H₂O₂ and pH value of solution was discussed更多还原