• Elastomers and Composites
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• v.41 no.4
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• pp.260-267
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• 2006

SBR (styrene-butadiene rubber; 25 wt% of solid contents) nanocomposites reinforced with OLS(organically modified layered silicates) were manufactured via the latex method. Two types of OLS are prepared, i.e. dodecylamine (primary amine) modified montmorillonite (DA-MMT) and N, N-dimethyldodecylamine (tertiary amino) modified MMT (DDA-MMT). X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to characterize the layer distance of OLS and the morphology of the nanocomposites. SBR nanocomposites reinforced with ternary phase filler (carbon black/silica/OLS) systems also manufactured. Dynamic mechanical thermal analysis (DMTA) was performed on these composites to determine the loss factor (tan $\delta$) over a range of temperature($-20^{\circ}C{\sim}80^{\circ}C$). The results showed that there was significant changes on the values or tan $\delta$ with the addition of small amount of the OLS. By increasing the contents of OLS, the values of tan $\delta$ at $0^{\circ}C$ increased but those of tan $\delta$ at $60^{\circ}C$ decreased with increasing OLS contents.

• Elastomers and Composites
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• v.41 no.1
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• pp.27-39
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• 2006

In this study, modified DA-MMT filled NR/DA-MMT nanocomposites were manufactured by a latex method and a compounding method. Cure characteristics and mechanical properties of the Cloisite 15A, carbon black, Na-MMT filled NR compounds and the DA-MMT filled NR compound by a latex method were also evaluated. The filler content of all compounds was 10phr except the carbon black filled compound. Degree of intercalation and dispersion was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). According to the XRD diffraction pattern and TEM analysis, extensive intercalation and homogeneous dispersion of the clay were obtained after the two-roll milling. Although the layer distance was increased, some parts of DA-MMT showed the layer distance of Na-MMT after vulcanization. DA-MMT filled NR compounds showed the highest ODR torques, tensile strength, modulus, and tear energy. The NR/DA-MMT nanocomposite (by a latex method) compared with a NR/DA-MMT nanocomposite (by a compounding method) was found that the improvement of the mechanical properties was mainly due to the degree of dispersion of the clay.

• Elastomers and Composites
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• v.38 no.1
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• pp.81-87
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• 2003

In this work, $Fe_3O_4$ (magnetite), conductive filler was prepared from $FeCl_2{\cdot}4H_2O,\;(CH_2)_6N_4$ (hexamethylene tetramine), and $NaNO_2$, followed by mixing with crystallizable chloroprene rubber(CR). The influence of conductive filler content on the properties of the conductive composite was studied and temperature dependence of the electrical conductivity (${\sigma}$) was also investigated. It is found that the percolation threshold concept holds true for the conductive particle-filled composite where ${\sigma}$ indicates a nearly sharp increase when the fraction of magnetite in the mixture exceeds 27%. The temperature dependence of ${\sigma}$ is thermally activated blelow or at the $P_c$. Magnetite acts as reinforcement and conductive filler for CR rubber. Moreover, it is shown that the composite with magnetite of 50 phr gives the most significant mechanical properties for tensile strength and elongation at break, which is due to the formation of optimum physical interlock and crosslinking. The results of 100%, 200%, and 300% moduli suggest that the moduli are related with reinforcement effect of magnetite and viscosity of the blend.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.115-126
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• 2014

In order to improvement of the perceptive of health state and the motivation, this study suggests the ways and design forms which provide PHR information customizing individual attributes as well as guidelines through a decision support system and services which integrate medical information visualization. Expression methods using the color, form, position in order to visualization based on images improved performance of information awareness by changing radar chart from existing information which provide only numerical figure. The methods providing a graphic figure which seems like beads of blood which shows the result of blood tests would also arise patient's attention. They gives the patient's information which is able to compare their health status and normal status and visualizes the records as a human figure in order to perceiving their status as well. The visualization showing the position of human body figures marks in inspection elements located in position of relevant organs. The method also uses icons represent examination results so they improve attention of the results and shorten recognize times.

• Journal of Adhesion and Interface
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• v.23 no.2
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• pp.25-32
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• 2022

There has been a growing demand for water based-type PSA due to environmental regulations for solvent-type PSA. And accordingly, there is a growing expectation as well for tackifiers used to compensate for the problem of deterioration of physical properties. Therefore, In this study, water-based tackifiers were synthesized by changing the contents of hard and functional acrylic monomers CHMA, IBOA, and AA. And these were added to the pressure-sensitive adhesive at 10 phr and their physical properties were compared. Tackiness slightly decreased as CHMA increased and IBOA decreased. Since the intermolecular bonding force increased due to the increase in AA content, the lower the AA content showed better results. Peel strength increased as the tackifiers were added because the fluidity of the polymer chain increased. And higher AA content showed better results because more hydrogen bonds were formed. The holding power tended to decrease as CHMA increased because the content of IBOA relatively decreased which has a large influence on the holding power. And higher AA content showed better results.

• Elastomers and Composites
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• v.32 no.5
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• pp.309-317
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• 1997

Estimation of the dielectric properties of insulating silicone rubbers added reinforcing fillers $(SiO_2,\;0{\sim}140phr)$ are very important to investigate the polymer structure. The characteristies of the dielectric absorption in insulating silicone rubbers were studied in the frequency range from 30Hz to 1MHz at the temperature range from $0{\sim}170^{\circ}C$. In the case of non-filled specimen, the dielectric loss is due to the syloxane which is the main chain of silicone rubber at the low temperature below $50^{\circ}C$ and the frequency at 330Hz, and is due to methyl and vinyl radical over the frequency of 1MHz. It is confirmed that the methyl radical or the vinyl radical becomes thermal oxidation at the high temperature over $100^{\circ}C$ and then the dielectric disperssing owing to the carboxyl radical Is appeared. In the case of filled specimen, the dielectric constant is in creased with the additives of reinforcing fillers due to the effect of interfacial polarization explained by MWS(Maxwell-Wagner-Sillars)'s law. The dielectric loss is decreased by the disturbance of reinforcing fillers that is permeated between networks.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.125-126
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• 1994

The chemorheological changes and kinetics during curing reaction of an silica filled epoxy system (DGEBA with curing agent Polyxoypropylenediamine) were investigated. This study concentrates on the influence of silica on the reaction kinetics and rheological behavior of the eopxy system. The concentration of the filler was varied 0~200phr. Curing behavior of the silica filled epoxy system was measured at various heating rates with DSC. Conversion was also measured by integrating the obtained DSC curve and Kinetic parameters measured by using the nonlinear regression method. DSC experiments showed that the presence of silica was found to accelerate the progress of the curing reaction and of reduce the heat of reaction compared with that of unfilled epoxy systems . Rheological experiments were conducted on a Physica by using a disposable parallel plate fixture. Material properites were measured such as the elastic modulus(G′), the loss modulus(G"), the loss tangent(tan $\delta$), and the viscosity was at the initial stahe, and the more the silica filler was added, and the lower the gel temperature was in the epoxy system. In this study it is concluded that the curing of the silica filled epoxy system was found to be accelerated, as silica was added to the epoxy compound.

• Journal of Forest and Environmental Science
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• v.33 no.1
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• pp.33-38
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• 2017

In this study, spray-drying yield and morphological characterization of spray-dried cellulose nanofibril (CNF) and TEMPO-oxidized nanocellulose (TONC) depending on spray-drying condition and surfactant addition was investigated. As spray-drying temperature increased, the yield of spray-dried CNF was increased. The highest spray-drying yields in both nanocelluloses were found at didecyl dimethyl ammonium chloride (DDAC) addition of 2.5 phr at all investigated temperatures. The spray-dried CNF was the sphere-like particle, but the spray-dried TONC showed both rod and sphere-like morphology. The average diameter of spray-dried CNF was decreased with increasing DDAC addition amount, resulting in the increase of specific surface area.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.679-685
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• 2008

This paper describes the degraded properties of between the charge and discharge current for ${\gamma}$-ray irradiated in electric power cable rubbers using in nuclear power generating station. The charge and discharge current of degradation in EPR(Ethylene Propylene Rubber), which were irradiated with the radiant capacity of 0.033 Mrad/h, have been measured in order to investigate the influence of the atmosphere(in amount of reinforcing agent, moisture absorption and heat treatment) on electrical properties. When ${\gamma}$-ray were irradiated on the EPR with more reinforcing agent from 4 to 40 Phr, charge and discharge currents was increase due to the amount of reinforcing agent. It was verified that the discharging and charging currents irradiated by ${\gamma}$-ray were higher than those that was not irradiated. The amount of the degraded current was more after moisture absorption than before moisture absorption. The charge and discharge current after heat treatment was similar to that of before heat treatment and it was decreased with the time elapsed. As these properties related with ${\gamma}$-ray irradiation dose, it is suggested that these properties can be utilized as a index of irradiation degradation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.9
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• pp.1511-1517
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• 2016

The aim of this study is to improve of properties for electrical AC insulation breakdown strength using epoxy/micro-nano alumina composites with adding glycerol diglycidyl ether (GDE:1,3,5g). This paper deals with the effects of GDE addition for epoxy/micro alumina contents (40,50,60wt%)+surface modified nano alumina(1_phr) composites. 14 kinds specimen were prepared with containing epoxy resins, epoxy micro composites and epoxy nano-micro alumina mixture composites. Average particle size of nano and micro alumina used were 30nm and $1{\sim}2{\mu}m$, respectively. The micro alumina used were alpha phase with Heterogeneous and nano alumina were gamma phase particles of spherical shape. The electrical AC insulation breakdown strength was evaluated by sphere to sphere electrode system and raising velocity 1kV/s. The AC breakdown strength decreased insulation properties of multi-composites according to increasing micro alumina and GDE addition contents.