• Journal of the Korean Graphic Arts Communication Society
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• v.23 no.2
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• pp.1-14
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• 2005

Generally, printing inks are composed of pigment, vehicle and additive. Among others, the vehicle transfers the pigment to substrate and then binds it on the surface. So, rheological properties of the vehicle are an important factor which has influence on printability. Thus, in this study, rheology of the vehicle was investigated by using rotational rheometer according to molecular weight of resin. Also, emlusion rheology of water in oil type and its microstructure were examined with increasing the shear rate. Consequently, the following results were obtained: (1) By viscometric flow test, zero shear viscosity and shear thinning index of vehicle increased with increasing the molecular weight of resin. (2) By relaxation and creep test, relaxation time and retardation time of vehicle increased with increasing the molecular weight of resin. (3) By frequency sweep test, crossover point of vehicle increased with increasing the molecular weight of resin. (4) G' and G" of emlusions increased with increasing the molecular weight by amplitude sweep test. (5) The shape of water drop in emlusions was changed to the capillary tube.

• Elastomers and Composites
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• v.51 no.3
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• pp.188-194
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• 2016

In this study, novel quaternary plastomers consisting of ethylene, 1-hexene, high ${\alpha}$-olefin, and divinylbenzene were prepared using Zr metallocene catalyst, borate type cocatalyst, and tri-isobutylaluminium. The molar ratio changes of 1-hexene and high ${\alpha}$-olefin (1-octene, 1-decene, and 1-dodecene) had an effect on the properties of the quaternary plastomers. The structure of the quaternary plastomers was characterized using $^1H$ NMR. Molecular weight properties, crystallinity, and thermal properties of the plastomers were determined by GPC, WAXS, and DMA, respectively. Compared with the terpolymers prepared in our previous study, molecular weight and molecular weight distribution of the quaternary polymers were very similar, whereas glass transition temperature ($T_g$) was very low. Also, hardness and tensile properties of the quaternary plastomers were measured.

• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.1
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• pp.45-59
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• 2011

According as gradually increasing the demand for Eco-friendly products it has been progressed fairly development at a field of printing and printing inks. The Inks are used by soy oil beginning of ink industry for preventing environment. Now it is possible to make Eco-friendly inks with vegetable ester. So it is not necessary to use petroleum-based solvents for preventing environment. But There is some problems if using vegetable ester to inks. Vegetable ester has high solubility, it causes misting and low viscosity of the Inks. So resin is required high performance. Thus, in this paper, I studied about the properties variation of the Varnish and inks According to using the phenolic modified rosin ester and Soy oil Methyl esters. The compared in order of average molecular weight by the GPC method, rheological properties were found by rotational rheometer, and emulsion behavior were compared by high speed emulsification tester.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.5
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• pp.60-67
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• 2011

Hemicelluloses pre-extracted from Korean mixed wood chip were investigated as a wet-end additive. Hemicelluloses dissolved in hot water and alkali solution were isolated by ethyl alcohol precipitation from pre-extractives. They showed molecular weight of 9,000 ~ 27,000 g/mol as revealed by size exclusion chromatography. The reduction of molecular weight through hot water extraction was caused by autohydrolysis. Chemical composition of the hemicelluloses were analyzed with high-performance liquid chromatography and UV-Vis spectroscopy. As the surface charge of isolated hemicelluloses were negative, the adsorption of hemicelluloses onto softwood unbleached kraft pulp fiber was promoted by poly-DADMAC. The physical properties of handsheets increased as the molecular weight of hemicellulose increased. On the other hands, the optical property decreased with hemicellulose adsorption.

• Korean Membrane Journal
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• v.5 no.1
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• pp.18-24
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• 2003

In order to improve the mechanical properties of the sulfonated polysulfone (SPSf) membranes previously synthesized in our laboratory, poly(vinyl alcohol) (PVA) was blended which is well known as the excellent physical and chemical properties. The resulting membranes blended with several molecular weight of PVA varying from 13,000 to 124,000 have been characterized to investigate the effect of PVA molecular weight in terms of ion conductivities, methanol permeabilities, water contents and ion exchange capacities for both heat treated and untreated membranes at 150$^{\circ}C$. The proton conductivity is decreased as the molecular weight of PVA increases. The plain SPSf-6.0 showed the proton conductivity of 0.078 S/cm whereas the blended membrane with M.W. 31,000 PVA indicated 0.04 S/cm. For methanol permeabilities, when PVA is added to SPAf-6.0, methanol crossover is increased because of the gain of the hydrophilicity from 3.4 to 6.5${\times}$10$\^$-6/ $\textrm{cm}^2$/s. For the annealed blended membranes (with M.W. 31,000 PVA), both the methanol corssover and proton conductivity showed very consistent values, about 2.3${\times}$10$\^$-6/ $\textrm{cm}^2$/s and 0.036 S/cm, respectively.

• Korean Journal of Food Science and Technology
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• v.42 no.6
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• pp.688-692
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• 2010

The aim of this study was to investigate the effects of molecular weight and concentrations of chitosan on the germination of brown rice. Brown rice was germinated at $30^{\circ}C$ for three days in various chitosan solutions. The germination rate of the brown rice increased with increasing concentrations of chitosan solution, and was higher in the chitosan solution than in water. GABA content increased with increasing germination time and chitosan solution concentration. As the molecular weight of the chitosan decreased, germination rate and GABA content increased in the brown rice. The GABA content of germinated brown rice using low molecular weight chitosan A in a 100 ppm solution was 5145.5 nmole/g. This is approximately a five times higher value than that of the water-germinated brown rice. Texture properties were enhanced in all the germinated brown rice samples in chitosan solution compared to the brown rice germinated in water. These results indicate that chitosan solution treatment can increase germination rate and GABA synthesis activity in brown rice during germination, and can also improve the texture properties of brown rice.

• Macromolecular Research
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• v.9 no.2
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• pp.84-91
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• 2001

Both A-B-A triblock and multiblock copoly(ester-ether)s consisting of poly(L-Lactide) and poly(oxyethylene-co-oxypropylene) were prepared and characterized. The preparation of the triblock copolymer was done by ring-opening copolymerization of L-lactide with a commercially available telechelic copolyether, Pluronic$\^$TM/(PN) by catalysis of stannous octanoate. The molecular weight and unit composition of the produced copolymers were successfully controlled by changing the L-lactide/PN ratio in feed. However, a high molecular weight copolymer incorporating PN in large amount was not obtained because the molecular weight of the resulting copolymer was limited at a high L-lactide/PN composition. The multiblock copolymer was synthesized by the copolycondensation of oligo(L-lactic acid) prepared by thermal dehydration of L-lactic acid, PN, and dodecanedioic acid as carboxyl/hydroxyl adjusting agent. This polycondensation proceeded by catalysis of stannous oxide to give multiblock copolymers with high molecular weight and wide range of compositions.

• Elastomers and Composites
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• v.33 no.2
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• pp.110-116
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• 1998

A new technology was introduced to the emulsion polymerization. It is the ultrasonic activation method which replaced a chemical initiator and the environmentally benign process. In this study, free radicals were produced by a pulse type ultrasound energy irradiation, then polystyrene latex was polymerized without chemical initiator. With ultrasonic energy density, the degree of polymerization, average molecular weight, and particle size were increased, but the polydispersity index for the molecular weight and the particle size were decreased. The optimum condition of emulsifier concentration and temperature was found to be 1.0 wt.% SDS and $40^{\circ}C$, respectively. As a result, the emulsion polymerization process without chemical initiator was proved to be comparable to common latex properties such as average molecular weight, molecular weight distribution, particle size, etc.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.878-888
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• 1994

In order to investigate the fracture behavior of ABS terpolymer under the tension and impact load, varing the content of rubber, molecular weight of SAN, content and kinds of lubricant, tension speed, the mechanical properties were measured and SEM pictures of fracture area were taken. Under the tension, the tensile strength increased as rubber content and lubricant content decreased, while molecular weight and tension speed increased. The deformation of area near fracture site did not occur as rubber content, tension speed and molecular weight decreased and liquid lubricant was used. And in the shape of fracture seemed phase seperation. Under the impact load, the notched izod impact strength increased as rubber content, molecular weight, ambient temperature and lubricant content increased. In the SEM picture, the strength was high white the fracture surface was small.

• Proceedings of the Korean Printing Society Conference
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• 2007.11a
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• pp.1-12
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• 2007

The rheological properties of an ink relate to its performance on the press and to the printing quality. So it is necessary to analyze the relationship between printability and the rheological properties of ink. Transfer rate of ink is one of the important factor deciding print quality. And it is concerned with rheological properties of ink. Thus, in this study, according to the molecular weight of rosin modified phenolic resin the rheological properties of ink were measured by rotational rheometer and then transfer equation of ink, density and gloss were mesured in order to examine the printability of ink.