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Lower Viscosity (lower + viscosity)
Selected AbstractsHigh-Temperature Rheology of Calcium Aluminosilicate (Anorthite) Glass-Ceramics under Uniaxial and Triaxial LoadingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2001Balakrishnan G. Nair The high-temperature creep behavior of two fine-grained (,3 ,m) anorthite-rich glass-ceramics was characterized at ambient pressure and under a confining pressure of ,300 MPa. Experiments were done at differential stresses of 15,200 MPa and temperatures of 1200°,1320°C. Of the two materials, one had a tabular (lathlike) grain structure with finely dispersed second phase of mullite, mostly in the form of ,3,5 ,m grains comparable to that of the primary anorthite phase, whereas the other had an equiaxed grain morphology with fine (,400 nm) mullite precipitates concentrated at the anorthite grain boundaries. The results of creep experiments at ambient pressure showed that the material with the tabular grain structure had strain rates at least an order of magnitude faster than the equiaxed material. Creep in the tabular-grained material at ambient pressure was accompanied by a significant extent of intergranular cavitation: pore-volume analysis before and after creep in this material suggested that >75% of the bulk strain was due to growth of these voids. The equiaxed material, in contrast, showed a smooth transition from Newtonian (n= 1) creep at low stresses to non-Newtonian behavior at high stresses (n > 2). Under the high confining pressure, the microstructures of both materials underwent significant changes. Grain-boundary mullite precipitates in the undeformed, equiaxed-grain material were replaced by fine (,100 nm), intragranular precipitates of silliminate and corundum because of a pressure-induced chemical reaction. This was accompanied by a significant reduction in grain size in both materials. The substantial microstructural changes at high confining pressure resulted in substantially lower viscosities for both materials. The absence of mullite precipitates at the grain boundaries changed the behavior of the equiaxed material to non-Newtonian (n= 2) at a pressure of ,300 MPa, possibly because of a grain-boundary sliding mechanism; the tabular-grained material showed Newtonian diffusional creep under similar conditions. [source] Coating window for double layer extrusion slot coating of poly (vinyl-alcohol) solutionsPOLYMER ENGINEERING & SCIENCE, Issue 10 2001Shih-Yuan Lu The expansion of coating windows for low-viscosity poly(vinyl-alcohol) (PVA) solutions is achieved via utilization of a higher viscosity PVA solution as the stabilizing carrier layer. It is found that PVA solutions of higher viscosities possess a higher degree of processability than those of lower viscosities, and can serve as a stabilizing carrier layer when coating lower viscosity PVA solutions. The stabilizing effect of the carrier layer enhances with increasing viscosity of the carrier layer, but reaches a saturation state at a high enough viscosity. It is further found that the coating defects occurring at lower maximum coating speeds are dominated by the lower, carrier layer, while those at higher maximum coating speeds are controlled by the upper, carried layer. Consequently, there exists an optimal layer flow rate ratio at which the coating window is the largest. A new type of coating defect, called spreading failure, is observed for coating situations involving a thin and much less viscous upper layer. [source] Production and quality evaluation of instant lassiINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 1 2009SANJAY R HINGMIRE Instant lassi was prepared from cows' milk standardized to 4% fat and 8.5% solids-nonfat and heated to 85°C for 30 min, followed by cooling at 37°C and adding 50% v/v lactic acid to adjust the pH to 3.4, 3.6 and 3.8. The sugar was added at the rate of 8%, 10% and 12% and mixed thoroughly in a Waring blender. The synthetic flavours vanilla, strawberry and pineapple were also added at the rate of 0.2% and stored at refrigeration temperature. The sensory evaluation of flavoured instant lassi adjusted to pH 3.8 and 12% sugar indicated no influence in colour, appearance or overall acceptability of compared to control. Among the different flavours used, pineapple-flavoured instant lassi scored highest for colour, appearance and overall acceptability. Both pH and sugar had significant effects, flavoured instant lassi having a higher specific gravity and lower viscosity than the control. [source] Synthesis, characterization, and cure reaction of methacrylate-based multifunctional monomers for dental compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Mousa Ghaemy Abstract The synthesis of 2,2-bis[(4-(2-hydroxy-3-methacryloxyethoxy)phenyl]propane (BHEP) and (1-methacryloxy-3-ethoxymethacryloxy-2-hydroxy)propane (MEHP) for use as the monomer phase in dental composites are reported. The monomers were prepared by the reaction of 2-hydroxyethyl methacrylate (HEMA) with diglycidyl-ether of bisphenol A (DGEBA) and with glycidyl methacrylate (GMA), respectively. The progress of the reaction was followed by measuring the disappearance of the epoxide group peak using FTIR and the structure of the monomers was characterized by 1H-NMR. BHEP and MEHP have lower viscosity because of the presence of long aliphatic spacer on both sides of the aromatic ring in BHEP and the absence of aromatic rings and the presence of only one hydroxyl group in each molecule of MEHP. Thermal curing of the monomers was conducted in a DSC using benzoyl peroxide as an initiator. Photopolymerization of the monomers was also conducted with the visible light using camphorquinone and N,N -dimethylaminoethyl methacrylate as the photoinitiating system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] NEW GENERATION OF HEALTHY SNACK FOOD BY SUPERCRITICAL FLUID EXTRUSIONJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2010K.Y. CHO ABSTRACT A supercritical fluid extrusion (SCFX) process has been successfully developed for the production of a novel healthy snack containing 40,60 wt% protein with unique porous structure and texture. Supercritical carbon dioxide (SC-CO2) injection rate and product temperature at the die were found to be critical to control the expansion and texture of the final product. Maximum cross-sectional expansion was obtained at 0.3 wt% added SC-CO2, whereas more uniform internal structure was achieved at 0.7 wt% SC-CO2 level. As whey protein concentrate (80 wt%) concentration was increased from 52.8 to 78.2 wt% in the formulation, the cross-sectional expansion of baked and fried products increased by 65.8 and 44.4%, respectively. It was observed that lower viscosity of whey protein compared with starch decreased expansion but helped enhance further expansion during post-extrusion drying. The finding showed that an extrusion process at the temperature below protein denaturation temperature using SC-CO2 can help to prevent hard texture due to the thermosetting property of whey protein and to create a uniformly expanded structure. The textural properties of SCFX chips were comparable to commercial extruded or fried chip products. PRACTICAL APPLICATIONS The American snack market is one of fast-growing markets in the world as snacking becomes more popular. Because of the increasing concerns about health, there is also an increasing demand for new healthy snacks as an alternative for fried starch-based snacks with low nutrient density. This study shows the potential of supercritical fluid extrusion (SCFX) technology for healthy snack food production containing whey protein. SCFX chips had uniform cellular microstructure that cannot be obtained using conventional steam-based extrusion. As supercritical carbon dioxide can deliver certain flavors, an expanded snack not only with high nutrient density and unique texture but also with encapsulated flavors can be produced using the SCFX process and can be marketed as a novel healthy snack. [source] Comparison of Texture of Yogurt Made from Conventionally Treated Milk and UHT Milk Fortified with Low-heat Skim Milk PowderJOURNAL OF FOOD SCIENCE, Issue 6 2004W. Krasaekoopt ABSTRACT: The textures of yogurt made from ultra-high temperature (UHT) treated and conventionally treated milks at high total solids were investigated. The yogurt premixes, fortified with low-heat skim milk powder to 16%, 18%, and 20% total solids, were UHT processed at 143°C for 6 s and heated at 85°C for 30 min using the conventional method. The onset of gelation was delayed in the UHT-processed milk compared with conventionally heated milk. During fermentation, the viscosity of yogurt made from UHT-treated milk at 20% total solids was close to that of yogurt made from conventionally treated milk with 16% total solids. However, after storage for , 1 d, the yogurt made from UHT-treated milk had lower viscosity and gel strength than the yogurt made from conventionally treated milk. The solids level had no influence on yogurt culture growth. [source] NUTRITIONAL, PHYSICAL AND SENSORY CHARACTERISTICS OF VARIOUS CHOCOLATE-FLAVORED PEANUT,SOY BEVERAGE FORMULATIONSJOURNAL OF SENSORY STUDIES, Issue 2 2005R.P. DESHPANDE ABSTRACT Mixture design and pilot-plant scale processing protocol were developed to obtain the best chocolate-flavored peanut,soy beverage formulation. Twenty-eight formulations were evaluated for nutritional (lysine content), physical (viscosity [,], visual stability index [VSI]) and nine sensory (consumer liking) attributes. Lysine contents (mg/g protein) (44.1,57.1) were close to the reference (51.0) and in the desirable range observed for other peanut-based beverages. Higher viscosity indicated lower consumer liking, but lower viscosity resulted in lower VSI. Formulation ,8 having 43.9% peanut, 36.3% soy protein isolate (SPI) and 19.8% chocolate syrup had the highest consumer liking and the best balance of physical properties (, = 41.5 mPa·s; VSI = 0.99). As compared to commercial chocolate milk (6 = slightly like to 7 = moderately like), it was rated higher for appearance (7.0), color (6.8) and sweetness (6.4). Two SPI formulations (,6 and ,7) and a soy flour formulation (,14) were rated highest for aroma (6.2), color (7.0) and flavor (6.0), respectively. [source] Morphology development of PC/PE blends during compounding in a twin-screw extruderPOLYMER ENGINEERING & SCIENCE, Issue 1 2007Bo Yin The morphological development of a polycarbonate/polyethylene (PC/PE) blend in a twin-screw extruder was studied using a scanning electron microscope (SEM). The effects of extrusion temperature, viscosity ratio (the ratio of the viscosity of the dispersed phase to that of the matrix), and the screw configuration on the morphology of the PC/PE blend during the extrusion were discussed in detail. It was found that the morphology of the dispersed particles and the interfacial adhesion between the dispersed phase and matrix were both influenced by the extrusion temperature. The dispersed phase had a spheroidal shape and a small size during the high temperature processing, and an irregular shape and a large size when it was processed at low temperature. The PC phase with a lower viscosity was easier to disperse and also to coalesce. Therefore, the deformation of the low-viscosity dispersed phase during the processing was more intense than that of the high-viscosity dispersed phase. By comparing the effects of the different screw configurations on the morphology development of the PC/PE blend, it was found that the melting and breaking up of the dispersed phase were mainly affected in the initial blending stages by the number of the kneading blocks. While a kneading block with a 90 degree staggering angle was used, the size of the dispersed particles decreased and the long fibers were shortened, the large particles were drawn by the additional kneading zone. Finally, all of these structures were completely changed to the short fibers. POLYM. ENG. SCI., 47:14,25, 2007. © 2006 Society of Plastics Engineers [source] Facile synthesis and characterization of star-shaped polystyrene: self-condensing atom transfer radical copolymerization of N -[4-(,-bromoisobutyryloxy)phenyl]maleimide and styrenePOLYMER INTERNATIONAL, Issue 10 2008Yun Cao Abstract BACKGROUND: Generation of stars around in situ formed cores provides a facile approach to star-shaped polymers. Therefore the self-condensing atom transfer radical copolymerization (SCATRCP) of N -[4-(,-bromoisobutyryloxy)phenyl]maleimide (BiBPM) and a large excess of styrene (St) was investigated. RESULTS: BiBPM and St formed a charge transfer complex (CTC), which underwent the SCATRCP, leading to the branched core initiating the atom transfer radical polymerization of St, finally giving star-shaped polystyrene (PS). Kinetic and structural study showed that a higher dosage of BiBPM resulted in an enhanced polymerization rate, a higher degree of branching and a larger number of short PS arms. Differential scanning calorimetry suggested that the glass transition temperature of the star-shaped PS decreased with molecular weight. Melt rheometry showed that even a slightly branched architecture of the PS led to a significantly lower viscosity; both the melt flow index and the activation energy increased with the degree of branching. CONCLUSION: Due to the preferential consumption of BiBPM and formation of a CTC, even a very low dosage of BiBPM could lead to star-shaped PS, which, in comparison with linear analogues, could possess much better melt fluidity. Copyright © 2008 Society of Chemical Industry [source] Numerical Simulation of Thrombus Aspiration in Two Realistic Models of Catheter TipsARTIFICIAL ORGANS, Issue 4 2010Giancarlo Pennati Abstract Thrombus aspiration catheters are devices used to remove a blood clot from a vessel, usually prior to angioplasty or stent implantation. However, in vitro results showed that the use of different commercial devices could produce very different thrombus removals, suggesting a primary dependence on the distal tip configuration of the catheter. A computational methodology based on realistic catheter tip modeling was developed to investigate the factors affecting the thrombus suction. Two different designs were considered, either with a single central lumen or a combination of central and side holes. First, steady-state aspiration of distilled water from a reservoir was simulated and compared with experimental tests. Subsequently, the aspiration of a totally occlusive thrombus, modeled as a high viscous fluid, was simulated solving a complex two-phase (blood and thrombus) problem. In particular, the benefit of additional openings was investigated. Good matching between the steady-state experimental and numerically simulated hydraulic behaviors allowed a validation of the numerical models. Numerical results of thrombus aspiration showed that the catheter with central and side holes had a worse performance if compared with the single central lumen catheter. Indeed, the inlets in contact with both blood and thrombus preferentially aspirate blood due to its much lower viscosity. This effect hindered the aspiration of thrombus. The amount of aspirated thrombus highly depends on the complex, two-phase fluid dynamics occurring across the catheter tips. Results suggested that location of additional holes is crucial in the catheter aspiration performance. [source] | |||||||||||||