含活性侧基马来酰亚胺/苯乙烯共聚物的合成与性能研究

合成了含活性侧基的苯乙烯/N-对羟苯基马来酰亚胺共聚物(SHMI),使某些具有特定功能的有机小分子接枝到聚合物主链上.用FTIR,NMR及GPC研究了其化学结构,并用DSC和TGA研究了其热转变和热降解性能.结果表明,SHMI是交替共聚物,其玻璃化转变温度(Tg)高达526K,于661K开始降解,降解动力学遵循Arrhenius方程,有良好的溶解成膜性能.     

Zur Darstellung der Verkleisterungseigenschaften der Stärke in Rotationsviskosimetern

Zusammenfassung Das Verkleisterungsverhalten einer Stärke oder eines stärkehaltigen Materials (Mehl) wird üblicherweise mittels einer kontinuierlichen Viskositätsmessung bei definiert steigenden Temperaturen in einem Rotationsviskosimeter mit Relativ-Meßkörpern erfaßt. Die Strömungsverhältnisse in einer solchen Meßeinrichtung werden phänomenologisch beschrieben, der Einfluß der Konzentration der Mehlsuspensionen und der Teige (15–60% Trockensubstanz) und der Temperatursteigerungsgeschwindigkeit (0,5–3,0 °C/min) auf das Meßergebnis wird untersucht. Beide Meßparameter bewirken deutliche Veränderungen sowohl in der Viskosität der Suspension bzw. der Teige, als auch in der Temperatur als Zeitfunktion, bei der die Viskositätsveränderungen stattfinden. Dieses Verhalten wird mit dem zeitabhängigen Wasserbindevermögen, der Quellung und der Verkleisterung der Korninhaltsstoffe gedeutet, und es wird auf die Notwendigkeit hingewiesen, diese Tatsache bei der Auswertung und dem Vergleich der Verkleisterungskurven zu berücksichtigen.

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The glutinization behaviour of starch or starch-rich materials (such as flour) is usually determined by means of the continuous measurement of viscosity at a defined rate of temperature increase in a rotational viscometer providing relative measurements. The flow behaviour in such a measuring device is described phenomenologically and the influence of the concentration of the flour slurries or doughs (15–60% dry substance) and the rate of temperature increase (0.5 to 3.0 °C/min) on the results is investigated. Both parameters cause distinct changes in the viscosity of the slurries or doughs as well as in the time-dependent behaviour of the temperature at which the changes in viscosity occur. This behaviour is explained in terms of the swelling, the glutinization and the time-dependent water absorption capacity of the flour. It is pointed out that these facts must be considered when evaluating and comparing glutinization curves.

Veröffentlichung Nr. 5077 der Bundesforschungsanstalt für Getreide- und Kartoffelverarbeitung in Detmold, vorgetragen auf der Jahrestagung der Deutschen Rheologischen Gesellschaft in Ulm vom 7.–10. März 1983.     

A straight way to regioselectively functionalized polysaccharide esters

The topic of this contribution ID a novel method for regioselective esterification of starch, similar polysaccharides and cyclodextrines avoiding protecting or activating groups. A broad spectrum of polysaccharides could be acylated selectively at the C-2 position of the AGU. The reaction principle ID based on a transesterification of a carboxylic acid vinyl ester with the hydroxyl groups of the polymer ID the presence of a low molecular salt. The interaction of the reaction participants and the solution state of the polysaccharides enable this selective functionalization. The structure characterization of the new polysaccharide derivatives ID carried out by NMR spectroscopy, especially the HMBC technique, after a complete esterification of the free hydroxyl groups with a suitable carbon acid anhydride.     

Fabrication of starch blend films with different matrices and their mechanical properties

The objective of the study was to determine the effects of molecular sizes of amylose (AM) and starch granules on the mechanical properties of thermoplastic starch (TPS) blend films. Leached amylose solution from cassava (CS_ AM) and mung bean (MB_AM), and two forms of amylopectin (AP) (granular; g and non-granular; ng) of waxy cassava (WxCS) starch were used. Four types of film matrices were fabricated and all TPS blend films contained same amount of AM and glycerol. Results displayed that molecular weight profiles of starch films and presence of granule remnants significantly controlled the film matrix formation, types of crystal formation, and percent of relative crystallinity (%RC) (p < 0.05). Tensile property of TPS films was controlled by %RC and presence of granule remnants. Percent elongation at break (%E_b) of TPS films increased when the films had a large range of molecular weight distribution (from 5.5 × 10⁷ g/mol to 0.4 × 10⁵ g/mol) and contained a high weight fraction (~58%) of starch molecules with M_w~0.4 × 10⁵ g/mol.     

喇曼光谱法测定单个大米淀粉微粒糊化过程的实时研究

在特定加温模式和过量水分条件下,采用激光光镊喇曼光谱系统研究了单个大米淀粉微粒的糊化行为,获得了整个糊化过程的喇曼光谱.以光谱峰高的变化标记糊化过程,进一步验证了477 cm-1峰归属为淀粉分子骨架振动的事实.通过分析C-O-H基团相关特征峰1 052、1 083、1 127、1 339 cm-1的变化情况研究大米淀粉颗粒糊化过程中的速率问题.结果显示:糊化开始后,相关特征峰在过程中呈增强趋势,随着时间增加,温度升高,速率加快,直至糊化结束.     

基于异谱二维NIR-IR相关判别掺杂牛奶

为更快、更准确的判别掺杂牛奶和纯牛奶,将二维异谱NIR-IR相关谱与多维偏最小二乘判别(NPLS-DA)相结合,建立了掺杂牛奶与纯牛奶NPLS-DA模型。首先,准备并配置纯牛奶和浓度范围为0.01~1g·L-1掺杂淀粉牛奶样品各36个,并在室温的条件下采集所有样品的一维近红外透射光谱和中红外衰减全反射光谱。接着,计算了所有样品在4 200~4 800和900~1 700cm-1范围的同步二维NIR-IR相关谱,研究了其二维相关谱特性,并指出虽然该技术可提供更多的信息,但由于掺杂物微量,仍旧无法根据相关图谱直接对比判定牛奶是否掺杂,需要借助模式识别的方法进行判别。最后,将同步二维NIR-IR相关谱与NPLS-DA结合建立掺杂牛奶与纯牛奶的判别模型,该模型对校正集内部样品和预测集外部样品的判别正确率分别为95.8%和100%。此外,为了比较,分别建立了基于二维NIR和IR相关光谱的NPLS-DA模型,两模型对未知样品的判别正确率均为95.8%。研究结果表明:采用NIR-IR相关谱的NPLS-DA模型能提供更好判别结果。该方法可有效提取食品中掺杂物的特征信息,为检测掺杂食品提供了一个新的方法。     

Molecular Dynamic Evaluation of starch-PLA blends nanocomposite with organoclay by proton NMR relaxometry

Starch and PLA were used alone and in blends to prepare nanostructured materials using both hydrophilic and organophilic clays, and PVA. All nanostructured materials were obtained by the solution intercalation method using water and chloroform as solvents. These systems were characterized by using conventional X-ray diffraction (XRD), conventional NMR and the non-conventional fast field cycling (FFC) NMR technique. The spin-lattice relaxation times were measured as a function of the Larmor frequency. The FFC results showed that the starch has only one relaxation time related to the amorphous region. PLA hybrids presented two distinct spin-lattice relaxation times. The blends of the two polymers also showed two relaxation times. The renormalized Rouse formalism was applied to describe the polymer molecular dynamics behavior in the studied systems containing starch. By adding clay or PVA, differences could be observed in relaxation time corresponding to the more amorphous region, indicating that, when adding clay and PVA, the effect that each has on the dynamics of the mixture is cancelled out.     

Kinetic Investigations of Reactions with Maleic Anhydride Copolymers and Model Compounds

Alternating copolymers that contain maleic anhydride (MAn) as a component occur in two different stereochemical configurations which are differentiated by their reactivity. Model compounds, 2, 3-dialkylsuccinic acids and their anhydrides, were investigated and it was demonstrated that there is a distinct difference between threo and erythro configurations in their chemical and physical behavior. Both configurations also occur in the alternating copolymers. Beside the model compounds, the alternating copolymers ethylene-MAn, propylene-MAn, and styrene-MAn were investigated in their reactions with amines, alcohols, and water (hydrolysis). The cis configurations showed the higher reaction rates. Reactions of the anhydride moieties with equimolar amounts of aniline, ethanol, and water demonstrated that reactions follow second-order rate laws. With excess reactant, the reaction follows a pseudo-first-order rate law. The rate constants depend on the degree of polymerization and on the comonomer. Increasing steric hindrance and molecular weight lead to a decrease of the reaction rate. Catalysis of the hydrolysis reaction by tertiary amines results in similar rate constants for the configurations of the substituted succinic acid anhydrides. The reasons are discussed.     

Starch - A suitable fuel in new low-temperature combustion-based synthesis of zinc aluminate oxides

Starch has been tested as single-fuel and in a two-fuel mixture, together with N-methylurea, in a new combustion-based synthesis of zinc aluminate oxides, using different fuel compositions and equivalence ratios Φ_e (Φ_e = fuel/oxidant). The combustion process has been analyzed by simultaneous thermal analysis. The corresponding oxides were characterized by X-ray diffraction analysis, UV-Vis spectroscopy, scanning electron microscopy and BET investigations. Crystal structures were refined by Rietveld method. The morphology, specific surface area and optical properties of the obtained zinc aluminate have proved to be strongly dependent on the fuel nature and composition. The lowest crystallite size (131 Å) is achieved for the oxide generated from the starch-based precursor, while the highest surface area (20.69 m²/g) has been obtained for a 3:1 N-methylurea/starch fuel composition. The non-zero value for microstrain has indicated spinelic defects in the starch-fuel corresponding oxide. UV-Vis spectroscopic analysis have confirmed the intrinsic properties of the resulted mixed metal oxide, but also shows the presence of a certain disorder degree for all the other samples. The superior values of the band gap (4.2-4.7 eV) for the obtained oxides relative to the bulk case (3.8 eV) are the result of the nanometric dimensions of the particles.