• Elastomers and Composites
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• v.48 no.1
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• pp.18-23
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• 2013

Nylon 12 elastomer was slightly crosslinked in molten state by the addition of small amount of dicumyl peroxide (DCP) as a crosslink agent and triallycyanuate (TAC) as a co-agent during melt compounding at $160^{\circ}C$ in an internal mixer. The effect of the peroxide crosslinking on mechanical, dynamic mechanical and rheological properties of the nylon 12 elastomer was investigated by means of tensile testing, dynamic mechanical analysis (DMA) and small amplitude oscillating rheometer, respectively. With modification, there is an improvement in tensile modulus and Young's modulus with decease in elongation at break. DMA results for peroxide modified nylon 12 elastomers demonstrated that the glass transiaiton temperature of PTMG segment shifted to higher temperature and the storage modulus remained constant above the melting temperature of nylon 12 segments. Melt rheological studies revealed that the peroxide modified nylon 12 elastomer exhibited a more solid like behavior and stronger shear thinning behavior compared to neat nylon 12 elastomer, which was more prominent at higher TAC content in the polymer matrix. The peroxide modified nylon 12 elastomer exhibited good elastic recoverability and improved mechanical properties without sacrificing melt processibilty, and especially the service temperature range increased as compared to neat nylon 12 elastomer.

• Polymer(Korea)
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• v.38 no.6
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• pp.767-773
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• 2014

Rheological and electrical properties of polystyrene (PS)/carbon nanotube (CNT) nanocomposites via coagulated precipitation were investigated. Chemical modification and surfactant wrapping of CNT to improve the dispersion of CNTs may reduce the intrinsic properties of pristine CNT. To avoid this problem, PS and CNTs were dissolved and dispersed in dimethylformamide and then PS/CNT nanocomposites were prepared by the coagulated precipitation of CNT-dispersed PS solution in water. The coagulated precipitation method was highly effective enhancing the electrical conductivity of nanocomposites. Furthermore, the effect of adding poly(styrene-co-divinylbenzene) crosslinked particles to PS matrix on the rheological and electrical properties was investigated. With the addition of the crosslinked particles, the electrical percolation threshold of CNT reduced to 0.25 wt% and electrical conductivity increased further. It is speculated that CNTs in the volume occupied by crosslinked particles helped electrical pathway formation.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.127-131
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• 1992

The effects of chlorine treatment on the rheological properties (farinogram, extensogram, amylogram) of soft white wheat flour were studied by treating flour with different amounts (1, 2 and 4 ounces per 100 pounds of flour) of liquidized chlorine gas. Departure time, water absorption and dough stability increased while mechanical tolerance index decreased as the level of chlorine increased. It was appeared that extensibility and resistance at chlorine level of 1 to 2 oz was appropriate for baking properties of flour compared to those of untreated wheat flour. The temperature at maximum viscosity increased gradually with increasing levels of chlorine. It was noted that maximum viscosity was greatly increased at 4 oz compared to those of lower levels of chlorine treatment.

• The Korean Journal of Food And Nutrition
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• v.18 no.4
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• pp.287-294
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• 2005

Three different gruels; $100\%$ rice, $70\%$ rice and $30\%$ sprouted black bean with sprout, and $100\%$ rice and $70\%$ sprouted black bean, were prepared. Organoleptic, chemical and rheological properties were compared according to the heating time and the quantity of water. Regarding to the the rheological properties, the gruel with $30\%$ rice and $70\%$ sprouted black bean with sprout revealed the lowest level of solidity and the highest level of viscosity among these three kinds of gruels. The chemical properties; pH, total sugar content and amylose content were similar each other. In terms of organoleptic properties, the best gruel was made with $30\%$ rice and $70\%$ sprouted black bean with sprout. In addition, the best cooking condition was found that 9 times of water to the weight of rice and sprouted black bean with sprout, was used follows by 40 minutes' heating.

• Journal of Dairy Science and Biotechnology
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• v.36 no.4
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• pp.196-207
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• 2018

This study was carried out to investigate the rheological properties and composition of unsaturated fatty acid of farm butter made from the milk of cows grazing at high mountain pasture in Pyronogchang SKY ranch (above sea level, 935 m). From two groups containing 7 cows each, a group was fed in-door with TMR (total mixed ration) feed and whereas the other group was grazed pastures for 12 h. The daily intake of feed on basis of dry matter (DMI), milk yields, concentration of milk constituents, and fatty acid profile of pasture milk were compared with control TMR milk. In addition, the physiochemical properties and composition of unsaturated fatty acids of the butter were also compared with those of the butter made from control TMR milk. Upon comparison, the health-promoting index (HPI) of fatty acids; the ratio of omega-6 fatty acids to omega-3 fatty acids (n-6 to n-3 UFA), the atherogenicity index (AI), and the ratio of linoleic acid to ${\alpha}$-linolenic acid (LA to ALA) was apparently improved in farm butter than those of control butter. Thus, it could make the dairy farm visitors to consume the farm butter containing the health-promoting fatty acids from the milk of cows grazing on mountain pasture.

• Advances in concrete construction
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• v.7 no.2
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• pp.87-96
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• 2019

Self-compacting concretes (SCC) are highly fluid concrete which can flow without any vibration. Their composition requires a large quantity of fines to limit the risk of bleeding and segregation. The use of crushed sand rich in limestone fines could be an adequate solution for both economic and environmental reasons. This paper investigates the influence of quarry limestone fines from manufactured crushed sand on rheological, mechanical and durability properties of SCC. For this purpose, five mixtures of SCC with different limestone fines content as substitution of crushed sand (0, 5, 10, 15 and 20%) were prepared at constant water-to-cement ratio of 0.40 and $490kg/m^3$ of cement content. Fresh SCC mixtures were tested by slump flow test, V-funnel flow time test, L-box height ratio, segregation resistance and rheological test using a rheometer. Compressive and flexural strengths of SCC mixtures were evaluated at 28 days. Regarding durability properties, total porosity, capillary water absorption and chloride-ion migration were studied at 180 days. For the two test modes in fresh state, the results indicated compatibility between slump flow/yield stress (${\tau}_0$) and V-funnel flow time/plastic viscosity (${\mu}$). Increasing the substitution level of limestone fines in SCC mixtures, contributes to the decrease of the slump flow and the yield stress. All SCC mixtures investigated achieved adequate filling, adequate passing ability and exhibit no segregation. Moreover, the inclusion of limestone fines as crushed sand substitution reduces the capillary water absorption, chloride-ion migration and consequently enhances the durability performance.

• Journal of Powder Materials
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• v.29 no.2
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• pp.99-109
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• 2022

Powder flowability is critical in additive manufacturing processes, especially for laser powder bed fusion. Many powder features, such as powder size distribution, particle shape, surface roughness, and chemical composition, simultaneously affect the flow properties of a powder; however, the individual effect of each factor on powder flowability has not been comprehensively evaluated. In this study, the impact of particle shape (sphericity) on the rheological properties of Ti-6Al-4V powder is quantified using an FT4 powder rheometer. Dynamic image analysis is conducted on plasma-atomized (PA) and gas-atomized (GA) powders to evaluate their particle sphericity. PA and GA powders exhibit negligible differences in compressibility and permeability tests, but GA powder shows more cohesive behavior, especially in a dynamic state, because lower particle sphericity facilitates interaction between particles during the powder flow. These results provide guidelines for the manufacturing of advanced metal powders with excellent powder flowability for laser powder bed fusion.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.247-251
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• 2023

Lecithin can self-assemble into reverse spherical micelles in organic solvents due to its amphiphilic properties. With additives such as D-sorbitol and water, the reverse spherical micelles are transformed into reverse cylindrical micelles by the morphology change of lecithin molecules. In this study, the rheological properties of lecithin/D-sorbitol/water mixtures were investigated. In addition, the small angle X-ray scattering (SAXS) technique was used to examine the shape and size of the formed nanostructures related to their rheological properties. Such mixtures are expected to be used in drug delivery and oleogels because of their high viscosity and viscoelastic behavior.

• Korean journal of food and cookery science
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• v.1 no.1
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• pp.53-56
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• 1985

The rheological models of acorn flour gels with different concentrations were investigated by stress relaxation test. The analysis of relaxation curves by successive residual method revealed that the rheological behavior of acorn flour gels could be expressed by the 7-element, generalized Maxwell model. The equilibrium modulus and modulus of elasticity increased by the increment of acorn flour concentration.

• Korean journal of food and cookery science
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• v.11 no.5
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• pp.552-556
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• 1995

The rheological properties of Korean white gruel at various concentrations (4-7%) and temperatures (30-60$^{\circ}C$) were investigated. The rheological behavior of Korean white gruel was evaluated by Herschel-Bulkley equation and showed typical Bingham psedoplastic behavior with yield stress. Flow behavior index was increased at over 5％ of rice content. Consistency index was increased by the increase of concentration of rice. But, measuring temperature was not effected in the flow behavior index and consistency index. Yield stress was increased by the incerase of concentration of rice and the decrease of measuring temperature. The activation energy of flow of Korean gruel increased from 7.646 to 32.949${\times}$10/Sup 6/ J/Kg$.$ mole by increasing concentration from 4％ to 7％. As the temperature increased from 30$^{\circ}C$ to 60$^{\circ}C$, B-value decresed from 1.214 to 0.947 Flow behavior index and consistency index was reduced during storage.