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Processing Properties (processing + property)
Selected AbstractsEffect of Alkyl Side-Chain Length on Photovoltaic Properties of Poly(3-alkylthiophene)/PCBM Bulk HeterojunctionsADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Abay Gadisa Abstract The morphological, bipolar charge-carrier transport, and photovoltaic characteristics of poly(3-alkylthiophene) (P3AT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blends are studied as a function of alkyl side-chain length m, where m equals the number of alkyl carbon atoms. The P3ATs studied are poly(3-butylthiophene) (P3BT, m,=,4), poly(3-pentylthiophene) (P3PT, m,=,5), and poly(3-hexylthiophene) (P3HT, m,=,6). Solar cells with these blends deliver similar order of photo-current yield (exceeding 10,mA cm,2) irrespective of side-chain length. Power conversion efficiencies of 3.2, 4.3, and 4.6% are within reach using solar cells with active layers of P3BT:PCBM (1:0.8), P3PT:PCBM (1:1), and P3HT:PCBM (1:1), respectively. A difference in fill factor values is found to be the main source of efficiency difference. Morphological studies reveal an increase in the degree of phase separation with increasing alkyl chain length. Moreover, while P3PT:PCBM and P3HT:PCBM films have similar hole mobility, measured by hole-only diodes, the hole mobility in P3BT:PCBM lowers by nearly a factor of four. Bipolar measurements made by field-effect transistor showed a decrease in the hole mobility and an increase in the electron mobility with increasing alkyl chain length. Balanced charge transport is only achieved in the P3HT:PCBM blend. This, together with better processing properties, explains the superior properties of P3HT as a solar cell material. P3PT is proved to be a potentially competitive material. The optoelectronic and charge transport properties observed in the different P3AT:PCBM bulk heterojunction (BHJ) blends provide useful information for understanding the physics of BHJ films and the working principles of the corresponding solar cells. [source] The Development of Light-Emitting Dendrimers for Displays,ADVANCED MATERIALS, Issue 13 2007L. Burn Abstract Dendrimers are now an important class of light-emitting material for use in organic light-emitting diodes (OLEDs). Dendrimers are branched macromolecules that consist of a core, one or more dendrons, and surface groups. The different parts of the macromolecule can be selected to give the desired optoelectronic and processing properties. The first light-emitting dendrimers were fluorescent but more recently highly efficient phosphorescent dendrimers have been developed. OLEDs containing light-emitting dendrimers have been reported to have external quantum efficiencies of up to 16,%. The solubility of the dendrimers opens the way for simple processing and a new class of flat-panel displays. In this Review we show how the structure of the light-emitting dendrimers controls key features such as intermolecular interactions and charge transport, which are important for all OLED materials. The advantages of the dendrimer architecture for phosphorescent emitters and the way the structure can be varied to enhance materials performance and device design are illustrated. [source] Development of low-fat mayonnaise containing polysaccharide gums as functional ingredientsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2010Hou-Pin Su Abstract BACKGROUND: The objective of this study was to develop a low-fat (LF) mayonnaise containing polysaccharide gums as functional ingredients. Xanthan gum (XG, 15 g kg,1), citrus fiber (CF, 100 g kg,1) and variable concentration of guar gum (GG) were used to formulate the optimum ratios of polysaccharide gums as fat replacers. The fat content in LF mayonnaise was reduced to 50% if compared with full-fat (FF) mayonnaise, and the products still maintained ideal rheological properties. RESULTS: The rheological parameters showed that there were no (P > 0.05) differences in yield stress, viscosity and flow behavior index between XG + 10 g kg,1 GG, CF + 5 g kg,1 GG and FF control. LF mayonnaises had lower caloric values and higher dietary fiber content than the FF counterpart. Scanning electron microscopy (SEM) micrographs illustrated that the network of aggregated droplets in LF treatments contained a large number of interspaced voids of varying dimensions. Furthermore, in a comparison of sensory evaluation of LF treatments with commercial and our FF mayonnaises, there were no (P > 0.05) differences in any sensory scores among XG + 10 g kg,1 GG control. CONCLUSION: This study shows that XG + 10 g kg,1 GG and CF + 5 g kg,1 GG could be used in LF mayonnaise formulations based on its multiple functions on processing properties. Copyright © 2010 Society of Chemical Industry [source] Seed-specific expression of the wheat puroindoline genes improves maize wet milling yieldsPLANT BIOTECHNOLOGY JOURNAL, Issue 8 2009Jinrui Zhang Summary The texture of maize (Zea mays L.) seeds is important to seed processing properties, and soft dent maize is preferred for both wet-milling and livestock feed applications. The puroindoline genes (Pina and Pinb) are the functional components of the wheat (Triticum aestivum L.) Hardness locus and together function to create soft grain texture in wheat. The PINs (PINA and PINB) are believed to act by binding to lipids on the surface of starch granules, preventing tight adhesion between starch granules and the surrounding protein matrix during seed maturation. Here, maize kernel structure and wet milling properties were successfully modified by the endosperm-specific expression of wheat Pins (Pina and Pinb). Pins were introduced into maize under the control of a maize ,- Zein promoter. Three Pina/Pinb expression positive transgenic lines were evaluated over two growing seasons. Textural analysis of the maize seeds indicated that the expression of PINs decreased adhesion between starch and protein matrix and reduced maize grain hardness significantly. Reduction in pressure required to fracture kernels ranged from 15.65% to 36.86% compared with control seeds. Further, the PINs transgenic maize seeds had increased levels of extractable starch as characterized by a small scale wet milling method. Starch yield was increased by 4.86% on average without negatively impacting starch purity. The development of softer maize hybrids with higher starch extractability would be of value to maize processors. [source] Preparation and properties of dipropargyl ether of bisphenol A-modified bismaleimide resins and compositesPOLYMER COMPOSITES, Issue 5 2008Zhuxia Rong A kind of modified bismaleimide resin, with good heat resistance and processing properties for advanced composites, was developed. The modifier, dipropargyl ether of bisphenol A (DPBPA), was prepared by a phase-transfer catalyzing procedure, characterized by FTIR, 1H NMR, and elementary analysis, and used to modify 4,4,-bismaleimidodiphenylmethane (BMDPM). The thermopolymerization of a DPBPA-modified BMDPM resin was followed up by FTIR. The curing of the resin was investigated by differential scanning calorimeter and gelation characterization. The relation of viscosity and temperature was used to characterize the processability of the resin. The results of DMA analysis showed that the cured DPBPA-modified BMDPM resins had a glass transition temperature higher than 320°C. The carbon fiber (T700) reinforced composites showed excellent flexural properties at ambient temperature and at 250°C. DPBPA could effectively improve mechanical properties without deteriorating heat resistance of the BMDPM resin a lot. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Preparation and properties of a novel high-performance resin system with low injection temperature for resin transfer mouldingPOLYMER INTERNATIONAL, Issue 9 2004Dr Aijuan Gu Abstract A novel high-performance resin system with low injection temperature for resin transfer moulding, M4506, was developed, which was made of 4,4,-bismaleimidodiphenylmethane, o,o,-diallyl bisphenol A, o,o,-diallyl bisphenol A ether, and 1,1,-bis(4-cyanatophenyl)ethane. The processing characteristics, thermal and mechanical properties of the system were studied, and the effect of differing stoichiometries of each component on the processing and performance parameters was discussed. Investigations show that the processing properties of the M4506 system are greatly dependent on the stoichiometries of each component in the formulations, while all the three formulations developed in this paper have good processing characteristics, their suitable injection temperature are between 40 and 50 °C, depending on their respective formulation. The three formulations exhibited outstanding heat resistance (Tg = 294,300 °C) and thermal stability, good toughness and high strength, evidence that the M4506 system is a potential candidate as a high-performance RTM matrix for advance composites as well as high-performance paints with no solvents. Copyright © 2004 Society of Chemical Industry [source] OPTIMAL COAGULANT CONCENTRATION, SOYMILK AND TOFU QUALITY AS AFFECTED BY A SHORT-TERM MODEL STORAGE OF PROTO SOYBEANSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2008ZHI-SHENG LIU ABSTRACT Soybeans were adjusted to water activities (Aw) from 0.60 to 0.81, and stored at 30C for up to 3 months. At 1-month intervals, soybeans were retrieved from the storage and processed into 10.5 Brix soymilk. The optimal coagulant concentration (OCC) for making filled tofu was determined using a titration method. Other soymilk characteristics, including total solids, protein, 11 S/7 S protein ratio, phytate, titratable acidity, pH and color, were also determined. Filled tofu was prepared from each stored soybeans with the respective OCC using MgCl2 or CaCl2. With increasing Aw or storage time, the OCC decreased significantly. The decrease in OCC was significantly correlated to the difference in soymilk titratable acidity and the change in soymilk pH. Soybean storage time slightly decreased the breaking stress and apparent Young's modulus of the filled tofu, particularly the MgCl2 coagulated tofu. With increasing Aw or storage time, the lightness and yellowness intensity of both soymilk and tofu decreased, whereas their redness intensity increased. PRACTICAL APPLICATIONS Tofu and soymilk are popular soybean foods. Using optimal concentration of coagulant in soymilk is the most critical step among many steps of unit operations during tofu manufacturing for achieving high quality tofu. Improper use of coagulant can lead to product failure and therefore significant economic loss for the manufacturers. The optimal coagulant concentration varies not only with processing condition, but also with soybean materials which are affected by variety and storage conditions. Acidity, pH and food color are important quality factors to influence taste and consumer acceptance. Soybeans are subject to storage and transportation before processing. Storage length and environmental humidity are two of important factors which affect soybean quality and processing property. This study provides very important information that is useful for the soymilk and tofu manufacturers in controlling product quality through the understanding of the chemistry and processing characteristics of stored soybeans. Manufacturers can utilize the methods presented in this article to calculate the optimal coagulant concentrations to avoid product failure and to produce the best quality products. [source] | |||||||||||||