【作者】 杨蔚宁；

【导师】 程备久； 陈培荣；

【作者基本信息】 安徽农业大学 ， 遗传学， 2008， 硕士

【摘要】 本文以高直链玉米淀粉为对象,运用现代观察和测试手段对其聚集态结构和理化性质进行了系统研究和表征,制备了高直链玉米淀粉热塑性流延膜和高直链玉米淀粉高取代度醋酸酯,并对其性能和结构进行了研究和表征。主要研究结果如下:1.高直链玉米淀粉颗粒表面并不平坦,形状多种多样,具有明显的偏光十字,位于颗粒的中心。淀粉颗粒粒径在3～30μm之间,体积平均粒径小于普通玉米淀粉。结晶属于B型结晶,与普通玉米淀粉不同,结晶度18%,大大低于普通玉米淀粉。糊化温度在120℃左右,明显高于普通玉米淀粉。组份绝大部分是碳水化合物,含有少量蛋白质和脂肪。水溶性高于普通玉米淀粉,膨胀度则低于普通玉米淀粉。糊透明度较低。表观黏度随温度的升高,先增大后减小,峰值出现在120℃左右。2.确立了以高直链玉米淀粉为原料,采用PVA、甘油、乙二醛及其它助剂交联、塑化制备全生物降解淀粉膜的最佳反应体系和最适加工工艺,并对薄膜的力学性能、流变性能和降解性能进行了测试。研究结果表明以高直链玉米为原材料制成的薄膜具有较高力学性能,拉伸强度和断裂伸长率分别可达14.12MPa和19.9%,比在同等条件下制备的普通玉米淀粉薄膜的分别高出70%和180%,可在一定程度上替代传统包装物。在土壤中能够完全降解并可在自然状态下一定时间内能够保持良好的力学性能。3.以高直链玉米淀粉为原料,冰醋酸和酸酐为改性剂,MSA为催化剂,制备了高取代度高直链玉米淀粉醋酸酯,研究了酸苷与葡萄糖残基比例、催化剂用量、反应温度、反应时间、淀粉种类等反应条件对取代度的影响。确立最佳反应条件为催化剂0.1mL,淀粉葡萄糖基与酸的物质量比1:5.3,反应温度75℃,反应时间3h,在最佳反应条件下取代度可达2.84。用傅立叶红外和X射线衍射对醋酸酯的结构进行了表征。红外光谱上羟基伸缩振动峰的减弱、羰基振动峰的增强和醋酸酯特征峰的出现表明乙酰基团确实被引入。X射线衍射图谱显示淀粉结晶结构被破坏,结晶度几乎为零。研究发现相同反应条件下,高直链玉米淀粉比普通玉米淀粉更容易进行醋酸酯改性。更多还原

【Abstract】 The special effect produced by increase of amylose content of high amylose starch is widely noticed by resaerches of material science,and the change of its physical and chemical properties is of great signification to improve of the machine performance of starch based degradabal material and advance of the modification and plastisizing propertis of starch.In this paper,with arnylose starch as object,properties and aggregate-state struture were studied and charactered detailedly by morden observe and testing measure,and influence of change of amylose starch molecule’s microstructure tO its macroscopical properties.Highly substitued acttylated amylose starch and high amylose starch thermalplastic cast film were prpared,of which stucture and properties were characterized.The main conclutions are as follow:1.Amylose starch granules’ surface is not smooth,with all kinds of shapes.Maize and waxy starch granules’ surface is smooth,with shape of polygon.Maltese Cross is clear and crossed in the center of granules.Granule size range of amylose starch is 3-30μm and its granules diameter of volume is smaller than that of maize starch.With the analysis of X-ray diffraction,amylose starch are attributed to type A of crystal type,which is different from maize starch.The value of crystal is about 20%,far lower than that of maize starch.Pasting tempreture is about 120℃,observably higher than that of maize starch.Almost all of the composition is carbohydrate,only very little protein and fat contained.Amylose starch is Of higher water-solubility and lower swell ability than maize starch and transparency is very small.Viscosity of starch paste increase with increase of tempreture at first,and then fall back, the peak value appears around 120℃.2.Amylose biodegradable themerplastic film was prepared with amylose starch,PVA, glcerol,glyoxal and so on.Optimal composition of reaction system and operating conditions were discussed.Properties of mechanics,rheology and degradable ability was tested too.The conclution showed that the film could redure certain pressure and pull and used as substitute of traditional wrappage.Could be easily and totally degrad in soil and keep good perfomance of mechanics in a period of time.3.Amylose starch acetates with high degree of substitution were synthesized by reaction of amylose starch and acetic acid/acetic anhydride catalyzed by MSA.The influences of reactants,reaction condition on DS of the high amylose starch acetates were discussed.The structure of the starch acetates has been characterized by infrared spectrum and X-ray diffraction.Best reaction system was determined:catalyzer 0.1mL,n(glucose):(acerbity)1:5.3, reaction tempreture 75℃,reaction time 3 hour.It was proved that amylose starch is easier to be acetated.Infrared spectra show that the hydroxyl groups of starch are really substituted since the stretching peak of hydroxyl decreases dramatically,the result of FTIR confirms that the difference between the structure of high amylose starch and the starch acetates increases with the introduction of acetyl.The result of X-ray diffraction shows that the crystal structure of high amylose starch a is damaged during substitution,the DS decreased frome about 20%to nearly 0.更多还原