【作者】 李丽娜；

【导师】 郭锦棠；

【作者基本信息】 天津大学 ， 材料学， 2007， 硕士

【摘要】 为了克服传统氧化剂制备氧化淀粉工艺复杂、氧化程度不高等缺点,本文采用新型绿色氧化剂二氧化氯制备氧化淀粉,并将合成的氧化淀粉作为基材制备可食性薄膜。本文以玉米淀粉为原料,二氧化氯为氧化剂,制备氧化淀粉。采用两种的方法得到氧化剂二氧化氯。一种方法直接以盐酸为活化剂,从稳定性二氧化氯中活化出二氧化氯;另一种方法是以氯酸钠为原料,硫酸为反应介质,盐酸为还原剂,制备二氧化氯。以氧化淀粉羧基含量和粘度为主要指标,考察反应物配比、反应时间、反应温度等因素对淀粉氧化反应的影响。红外光谱图表明产物中引入了羧基和羰基,证明淀粉被氧化。通过对氧化淀粉扫描电镜照片、透射电镜照片及X射线衍射的分析,二氧化氯氧化淀粉的反应不但在淀粉的表面进行,而且颗粒内部也有发生,主要发生在淀粉的无定形区或低结晶区。氧化淀粉与原淀粉相比,透光率增大,沉降体积减小,抗凝沉性增强,粘度降低,相对分子质量降低。随着氧化淀粉氧化程度的加深,相对分子质量降低,透光率增大,沉降体积减小,抗凝沉性增强,当氧化淀粉羧基含量≥0.513%时,24h内不发生凝沉现象。以自制的氧化淀粉为基材,甘油为增塑剂,海藻酸钠为增强剂,制备氧化淀粉基可食性膜。以膜的抗拉强度和断裂伸长率为主要考核指标,考察糊化温度、糊化时间、甘油浓度、海藻酸钠浓度、淀粉浓度对成膜性能的影响,确定成膜反应的影响因素。通过正交实验得出:对膜抗拉强度最主要的影响因素是氧化淀粉浓度,其次是甘油浓度和海藻酸钠浓度;对膜的断裂伸长率最主要的影响因素甘油浓度,其次是氧化淀粉浓度;对膜水滴透过时间的最主要影响因素是氧化淀粉浓度,其次是甘油浓度。X射线衍射表明,氧化淀粉基可食性膜的晶型为B型。与淀粉基可食性膜相比,氧化淀粉基可食性膜的抗拉强度增强,水溶性增大,水蒸汽透过率增大。随着基材氧化淀粉羧基含量的增加,膜的水溶性增大,水蒸汽透过率增大。更多还原

【Abstract】 For overcoming disadvantage of a traditional oxidant, such as the complex operation to synthesize oxidized starch and low oxidized degree of production, as a new innocuous oxidant, ClO2 were used to synthesize oxidized starch. And then the oxidized starch-based films were synthesized and characterized.In order to produce the oxidant (ClO2), two methods were studied. HCl was an activator to activate the ClO2 from the stable form. ClO2 was synthesized by means of which NaClO3 was deoxidized by a reducing agent HCl, and the acid bath was supplied by H2SO4. Effects of amounts and ratio of reactants, reaction temperature and reaction time on the oxidizing reaction were analyzed by carboxyl groups content and viscosity of oxidized starch.The morphology and structure of the oxidized starch was characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Infrared Spectroscopy (IR) and X-ray diffraction. Physical and chemical properties of oxidized starch were analyzed. Results showed that there were carboxyl groups and carbonyl groups in oxidized starch. Oxidation did not result in any significant changes in the degree of crystallinity of starch, implying that oxidation took place mainly in the amorphous region. Compare with the native starch, oxidized starch had lower retrogration, higher clarity, lower viscosity and lower relative molecular weight. The edible oxidized starch-based film was synthesized by oxidized starch, plasticizer (glycerol), rein forcer (sodium alginate). Effects of concentration of glycerol, sodium alginate and oxidized starch, reaction temperature, reaction time on capability of the film were analyzed according to tensile strength and elongation. Results showed that primary influencing factor on Tensile Strength was concentration of oxidized starch, primary influencing factor on elongation was concentration of glycerol, and primary influencing factor on blob permeation time was concentration of glycerol.The pattern of XRD showed by the oxidized starch based-film was B-type. Compare with native starch based-film, the oxidized starch based-film had higher Tensile Strength, Water vapor permeation and water-solubility. Water vapor permeation and water-solubility became higher according to higher carboxyl groups content of oxidized starch.更多还原