玉米淀粉与丙烯酸胺接枝共聚物的制备

本文研究玉米淀粉与丙烯酰胺接枝共聚物的合成工艺及其在造纸工艺中用作干强剂、助留/助滤剂的效果。研究表明玉米淀粉与丙烯酰胺的质量比为5:3.5,引发剂硝酸铈铵用量为0.2g,反应时间为3h,反应温度为62℃,聚合物质量较好。     

新型水溶性深度氧化玉米淀粉的制备及氧化机理

研究一种新型的多羧基水溶性氧化玉米淀粉的制备方法, 最佳制备条件为: 适量的自制催化剂, 以氧气为氧化剂, NaOH用量为21 g, 反应温度100 ℃, 反应时间3.0h. 在该条件下制备的氧化淀粉羧基含量为3.60%.采用X射线衍射分析（XRD）、 扫描电子显微镜（SEM）、 红外光谱分析（IR）以及羧基、 羰基含量的化学分析法等对氧化机理进行了探讨.     

Radioprotectors from pyrodextrins

Cornstarch heated in the range of 230–280°C depolymerized into pyrodextrins characterized by two-component EPR signals of relatively stable free radicals. These thermally generated radicals could serve as efficient scavengers for free radicals generated from pyrodextrins with the 200 Gy dose of γ-radiation. The most efficient traps/scavengers were produced from cornstarch at 250–280°C. IR data indicated incorporation of the OH groups to the pyrodextrins. These groups most probably originated from the OH· radicals formed by the radiolysis of water. EPR spectra provided evidence for trapping free radicals generated by γ-irradiation and for their subsequent annihilation on contact with pyrodextrins. Water affected radical processes occurring in pyrodextrins caused by γ-irradiation.     

萌发玉米淀粉流变学特性的研究

实验研究了萌发玉米淀粉在不同温度和质量分数时剪切速率和表观黏度的关系,计算出各温度和质量分数下萌发玉米淀粉的稠度系数(K)和流变指数(n).实验表明,由于萌发玉米淀粉结构的微细化,淀粉糊表观黏度随温度的升高减小;质量分数增大时萌发玉米淀粉剪切稀化不明显.同时,温度的升高流变指数变化较大,偏向于牛顿流体;而质量分数的增加则使萌发玉米淀粉保持良好的假塑流体状态.     

Research on the preparation of crosslinked starch chlorinated with sodium hypochlorite

0　IntroductionInrecentyears,thestudiesontheusesofagricultureproductssuchasnaturalorchemicallymodifiedstarchesforcontrolledand/orslowreleaseofagrochemicalshavebecomeanattractivearea[1 ,2 ] ,becausetheseproductsarebiodegradable,abundant,andcheap .Starch encapsulatedagrochemicalsexhibitmanyad vantages.Thecharacteristicsofimprovedefficiencyandextendedactivityofagrochemicals,economicalencapsulation ,biodegradablebehaviorofstarchmatrix ,lesspollutiontoenvironments,reducedtimesandamountofapplication…     

超声处理后的玉米淀粉与环氧丙烷的反应机理

研究了玉米淀粉经超声处理后的化学反应性能变化。将经超声处理的玉米淀粉与环氧丙烷进行反应,发现反应取代度（Ds）由未处理时的0．113提高到0.225以上,同时发现提高超声功率对反应取代度有一定的促进作用,但随着作用时间的延长,反应取代度提高不明显。采用偏光显微镜研究超声处理后玉米淀粉的结构,发现超声处理后玉米淀粉整个颗粒的结晶结构变化不明显;用扫描电镜观察发现部分淀粉颗粒表面出现大小不同的小孔,部分小孔分布十分均匀,呈蜂窝状,由此推断超声对淀粉的作用只发生在淀粉颗粒表面的无定形区。     

生物塑料聚(3HB-co-4HB)/玉米淀粉共混材料的制备与性能

以聚4–羟基丁酸酯摩尔分数为7.3%的聚(3–羟基丁酸酯–co–4–羟基丁酸酯)和玉米淀粉为原料,通过挤出熔融共混和注塑成型制备了P(3HB-co-4HB)/玉米淀粉共混材料.借用差示扫描量热仪(DSC)、热失重分析仪(TGA)和电子拉力机等考察了玉米淀粉含量对共混材料熔点、结晶度、热分解温度、耐水性及力学性能的影响.结果表明:随玉米淀粉含量增加,共混体系的结晶度减小,熔融温度降低,熔限变宽且出现明显的双峰;玉米淀粉含量为30份的共混材料热分解温度较纯P(3HB-co-4HB)-7.3略有降低,缺口冲击强度和断裂伸长率分别在淀粉含量为10份和20份达最佳,其值分别为4.95.kJ/m2和33.15%,较纯P(3HB-co-4HB)-7.3分别提高14.3%和147.76%.拉伸强度和弯曲强度则随玉米淀粉含量增加逐渐下降.     

Radioprotective thermally generated free-radical dextrins

Effect of doses of the X-ray radiation from 0 to 400 Gy upon granular cornstarch and dextrins （British gums, BG） thermally generated from it at 230--300℃ was recognized with quantitative EPR and IR absorption spectroscopy, molecular mass distribution in the depolymerization products, Scanning Electron Microscopy, and X-ray diffractometry. Fractal analysis of the profiles of molecular mass distribution showed that the depolymerization involved debranching of amylopectin. Roasting of cornstarch produced BG which differed in concentration and EPR parameters of stable free radicals from BG generated by X-ray radiation. Two types of stable free radicals, with Gaussian and Lorentzian shapes of EPR signals, were recognized. The shapes of the signals and temperature dependence on free radical intensity indicated exchanging interactions of the antiferromagnetic type, causing partial quenching of the spins at-196℃（77K）. Upon X-ray irradiation, new radicals were generated, the number and stability of which strongly depended on the types of radicals present before irradiation. These radicals slowly ceased because of a repolymerization of BG on storage.     

影响玉米淀粉质量分数检测结果的因素分析

运用单波长、双波长2种比色法对淀粉质量分数w进行测定,实验结果发现,后者更优,因其可有效排除其他物所造成的影响.直链淀粉波长在500和600nm、支链淀粉波长在550和680nm的条件下,当溶液pH值接近3.5、淀粉与碘化合物的反应时间在20min、标准曲线与样品测定环境温度控制在5℃温差时,淀粉w分析误差均达最小值.     

羟丙基玉米淀粉的性能及应用

研究了用微乳化法制备羟丙基玉米淀粉,确定了较佳的反应条件.实验表明,羟丙基化能大大提高玉米淀粉的粘度和糊透明度,使其在造纸施胶剂中应用效果良好.