• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.2 s.115
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• pp.43-51
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• 2006

Starch is widely used as an adhesive material in the paper and corrugated board industry. The adhesion problem of corrugated board is categorized by two main parts called zipper board and white glue line. The object of this research is to investigate the factors affecting the adhesion problem by the gelatinization of various starch solutions and dynamic penetration properties measurements of various commercial base paper and handsheets. Flow property of starch solution is affected by sodium hydroxide addition and reaction level. Absorption property of commercial base papers and handsheets is affected by sizing and stock composition. Optimum bonding between top/bottom liners and corrugated medium is accomplished by acceptable flow viscosity of mixed starch solution and proper adsorption characteristic of base paper.

• Textile Coloration and Finishing
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• v.30 no.2
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• pp.90-97
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• 2018

Hydrophilic reactive hot-melt polyurethane adhesive(HRHA) using a hydrophilic polyol having different molecular weight and NCO index was synthesized. This HRHA was synthesized using Polyethylene glycol(PEG) as a hydrophilic polyol, Polypropylene glycol(PPG) and Polycaprolactone diol(PCL) as hydrophobic polyols, and Methylene diphenyl diisocyanate(MDI) as an isocyanate. The changes in IR spectrum, viscosity and thermal properties of HRHA with different PEG molecular weights and NCO index were investigated, and the tensile strength and elongation of the HRHA casting film and the peel strength, moisture permeability and water pressure of the HRHA coated fabric were confirmed. In this experiment, as the molecular weight of PEG and NCO index increased, the adhesive strength, tensile strength, elongation and moisture permeability was increased but viscosity and Tg was decreased.

• Journal of the Korean Graphic Arts Communication Society
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• v.25 no.1
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• pp.109-120
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• 2007

In gravure printing, the amount of ink fill into the cells has a great effect on the qualities of final printed products. And printability of final products is determined by every kinds of variables. Ink transfer process is not verified scientifically because gravure cell is small and printing speed is rapid. In order to understand the ink transfer mechanism of conventional gravure, this study is performed using the Computational Fluid Dynamics Evaluation. Flow-3D simulation software is used for considering of Newtonian flow. Among the various factors, this study have dealt with gravure cell types used computer simulation in order to define distinctive features in ink flow in the cell. The results of simulation, it defined the distribution of pressure, speed, stream function, viscosity, shear rate, surface tension during the gravure printing. It is founded out the difficulties and characteristics according to the printing speed and viscosity of Gravure ink.

• Structural Engineering and Mechanics
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• v.63 no.1
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• pp.89-102
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• 2017

In this work, we present a theoretical framework to study the thermovisco-elastic responses of homogeneous, isotropic and perfectly conducting medium subjected to inclined load. Based on recently developed generalized thermoelasticity theory with fractional order strain, the two-dimensional governing equations are obtained in the context of generalized magnetothermo-viscoelasticity theory without energy dissipation. The Kelvin-Voigt model of linear viscoelasticity is employed to describe the viscoelastic nature of the material. The resulting formulation of the field equations is solved analytically in the Laplace and Fourier transform domain. On the application of inclined load at the surface of half-space, the analytical expressions for the normal displacement, strain, temperature, normal stress and tangential stress are derived in the joint-transformed domain. To restore the fields in physical domain, an appropriate numerical algorithm is used for the inversion of the Laplace and Fourier transforms. Finally, we have demonstrated the effect of magnetic field, viscosity, mechanical relaxation time, fractional order parameter and time on the physical fields in graphical form for copper material. Some special cases have also been deduced from the present investigation.

• Macromolecular Research
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• v.14 no.2
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• pp.187-193
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• 2006

Organoclay, was applied as a filler, in place of carbon black and silica, to a natural rubber (NR)/butadiene rubber (BR) blend. A compounding method was used to disperse and separate the layered silicates. The effect of a coupling agent on the vulcanizates was evaluated using both the silica and organoclay filled compounds. After the compounding processes were completed, the XRD diffraction peaks disappeared, but then reappeared after vulcanization. The scorch times for the organoclay-filled compounds were very short compared to those for carbon black and silica-filled compounds. The organoclay-filled compounds showed high values of tensile strength, modulus, tear energy, and elongation at the break. When ranked by viscosity, the compounds appeared in the following order: silica > silica (Si-69) > organoclay > organoclay (Si-69) > carbon black. Fractional hysteresis, tensile set, and wear rates were very consistent with the viscosity of the vulcanizates. The Si 69 coupling agent increased reversion resistance, the maximum torque values in the ODR, modulus, and wear resistance, but decreased elongation at the break, fractional hysteresis, and tension set of the vulcanizates.

• Macromolecular Research
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• v.17 no.12
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• pp.1021-1024
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• 2009

We successfully prepared high-flow polycarbonate (PC) by blending commercial PC with a low molecular weight PC oligomer. The oligomer was synthesized by the addition of a large quantity of mono functional phenol groups, and the chain end group was reacted with p-tertiary butyl phenol (PTBP) to block the reactivity. The viscosity average molecular weight ($M_v$) for the oligomer was about 4,000-5,000 g/mol, compared to ~19,000 g/mol for the PC blend obtained by blending 10 wt% of the prepared oligomer with the commercial grade PC ($M_v$ of 21,000 g/mol). The blended PC had a melt flow index of 45, which is 2.5 times higher, and a processing temperature that was $20^{\circ}C$ lower, than that of commercial grade PC having a similar $M_v$.

• Journal of the Korean Wood Science and Technology
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• v.22 no.1
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• pp.85-90
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• 1994

The flow properties of binder latices for paper coating were investigated, together with dynamic viscoelastic properties of latex films and electron micrographs of latices, under various conditions. The amphoteric latex, binder pigment latex and anionic latex were used in this work. The amphoteric latex has both anionic and cationic functional group on its surface. The binder-pigment with a core-shell structure has dual functions : plastic pigment and binder. The low shear viscosity of binder latices and clay slurry were measured with Brookfield vis cometer. At low-shear rates. the viscosity decreased with increasing particle size of latex. On the amphoteric latex surface, the carboxyl groups are assumed to be fully dissociated over the region of pH 9~12, but the density of negative groups seems to be increased because of the gradual decrease in the degree of dissociation of amino groups. Since the apparent particle size of latex increases with surface charge, the electroviscous effect can be observed. On the anionic latex surface, the charge density is assumed to be nearly constant above pH 8. However, below pH 8 the coagulation of particles could be observed probably because of the decrease in the charge density.

• Korean Journal of Materials Research
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• v.16 no.9
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• pp.533-537
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• 2006

The effects of binary solvent mixtures with various ratios of toluene and ethanol on the properties of slurries and green sheets were investigated. Viscosity of slurry was changed by varying the ratio of solvent mixture which affected the solubility of binder. The relative solvency behavior of a solvent mixture could be predicted with the Hildebrand solubility parameter(${\delta}$) and hydrogen bonding index( ${\gamma}$). The minimum viscosity, the best dispersion of binder, was reached at the composition of toluene:ethanol=4:6, which corresponded to our forecast. The mechanical properties of green sheets related to evaporation of solvents were influenced by the composition of the solvent mixture. At the azeotrope the skin was formed on a drying cast during the drying process because of fast evaporation. At a range of concentrations over 50wt% toluene, green sheets could not be fully dried at low temperature due to excessive toluene. The mechanical properties of green sheets were excellent at the azeotrope-like composition of toluene:ethanol=4:6 which has a little excess of toluene over the azeotrope.

• Journal of the Korean Ceramic Society
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• v.45 no.2
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• pp.99-104
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• 2008

Zeta potential, sedimentation bulk density and rheology in the dispersion system have been studied in terms of solid loading (40-55 vol%), and types of additives. Ammonium polymethacrylate, glycerol, ethoxylated acetylenic diol, and polyvinyl alcohol have been used as the dispersant, cryo-protectant, surfactant, and binder, respectively. Sedimentation density greatly increased upon adding dispersant; the effect was more pronounced with ionic alumina suspension compared with covalent silicon carbide. With further addition of cryo-protectant and surfactant to dispersant, the sedimentation density increased somewhat. The suspension viscosity generally behaviored in an opposite manner to the sedimentation density, i.e., high sedimentation gave low high-shear viscosity, indicative of low order structure formation in the suspended particles. Shear rate rheology in shear rate of $2-300\;sec^{-1}$ showed a shear thinning and its onset began at similar shear rate (${\sim}100\;sce^{-1}$), regardless of solid loading.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1806-1813
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• 2003

The stirred tank reactor is one of the most commonly used devices in industry for achieving mixing and reaction. Here we report on results obtained from the large eddy simulations of flow inside the tank performed using a spectral multi-domain technique. The computations were driven by specifying the impeller-induced flow at the blade tip radius. Stereoscopic PIV measurements (Hill et $al.^{(1)}$) along with the theoretical model of the impeller-induced flow (Yoon et $al.^{(2)}$) were used in defining the impeller-induced flow as superposition of circumferential, jet and tip vortex pair components. Large eddy simulation of flow in a stirred tank was carried out for the three different Reynolds numbers of 4000, 16000 and 64000. The effect of different Reynolds numbers is well observed in both instantaneous and time averaged flow fields. The instantaneous and mean vortex structures are identified by plotting an isosurfaces of swirling strength for all Reynolds numbers. The Reynolds number dependency of the nondimeansional eddy viscosity, resolve scale and subgrid scale dissipations is clearly shown in this study.