• Polymer(Korea)
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• v.39 no.1
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• pp.130-135
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• 2015

Cellulose has attracted much attention as potential reinforcements in green composites. In this study, polypropylene (PP)/cellulose composites were prepared by melt-blending followed by compression molding. To improve interfacial bonding between PP and cellulose, maleic anhydride-grafted polypropylene (MAPP) was used. Mechanical properties of the PP/cellulose composites were investigated by UTM and izod impact tester. Thermal properties of the PP/cellulose composites were investigated by TGA and DSC. SEM images for the fracture surfaces of the composites showed that the MAPP was effective in improving PP/cellulose interfacial bonding. Tensile strength and modulus of the composite were maxima when MAPP content, based on cellulose content, was 3 wt%. With increasing cellulose content, the impact strength of the composites decreased but the tensile strength and modulus increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.743-748
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• 2006

We investigated the flame retardancy and the mechanical properties of Nylon6 by using melamine-based halogen-free flame retardants(melamine cyanurate:MC-100 and melamine phosphate:MP-100). We chose the UL-94 method for flame retardancy and measured the tensile strength, flexural strength, flexural modulus by using UTM and impact strength by using Izod impact tester. We also tested the effect of nano-clay on flammability and mechanical properties. We obtained the V0 grade when the concentration of flame retardant was over 5 wt%. The tensile strength and flexural strength decreased and flexural modulus increased with the concentration of both flame retardant systems. The results showed that MC-100 system was better than MPP-100 system. Because of poor dispersion, we did not obtain the synergistic effect of nano-clay.

• Corrosion Science and Technology
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• v.3 no.3
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• pp.112-117
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• 2004

This work investigated the material properties of Ni-P-B alloy electrodeposits obtained from a Ni sulfamate bath as a function of the contents of the P and B sources($H_3PO_3$ and dimethyl amine borane complex(DMAB), respectively) with/without additives. Chemical composition, residual stress, microstructure and micro hardness were investigated using ICP(inductively coupled plasma) mass spectrometer, flexible strip, XRD, TEM and micro Vickers hardness tester, respectively. From the results of the compositional analysis, it was observed that P and B are incorporated competitively during the electrodeposition and the sulfur from the additive is codeposited into the electrodeposit. The measured residual stress value increased in the order of Ni, Ni-P, Ni-B and Ni-P-B electrodeposits indicating that boron affects the residual tensile stress greater than phosphorus. As the contents of the alloying element sources of P and B increased, crystallinity and the grain size of the electrodeposit decreased. The effect of boron on crystallinity and grain size was also relatively larger than the phosphorus. It can be explained that the boron with a smaller atomic radius contributes to the increase of residual stress in the tensile direction and the larger restraining force against the grain growth more significantly than the phosphorus with a larger atomic radius. Introduction of an additive into the bath retarded crystallization and grain growth, which may be attributed to the change of the grain growth kinetics induced by the additive adsorbed on the substrate and electrodeposit surfaces during electrodeposition.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.26-32
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• 2013

A digital image correlation(DIC) method is a whole-field measurement technique that acquires surface displacements and strains from images information which characterized a random speckle as intensity grey levels. Recently years, this DIC method is being developed and used increasingly in various research. In this study, we tried to apply to aluminum alloy(Al 6061-T6) using DIC method and strain gauge. DIC results demonstrated the usefulness and ability to determine a strain. The test specimen used in this study was an aluminum alloy(Al 6061-T6, thickness 1 mm). For a strain measurement, a strain gauge was attached at the center of a specimen. A specimen was lightly sprayed with a white paint and a black dot pattern was sprayed on its fully dried white surface to obtain a random speckle. The experimental apparatus used to perform the tensile test consisted of universal dynamic tester(5 kN; T.O. Co.) under displacement speed of 0.5, 1.0 and 3.0 mm/min. A Model 5100 B Scanner(V. Co.) used to obtain a strain. A CCD camera connected to a PC uses to record the images of the specimen surface. After acquisition, the images were transferred to PC where the DIC software was implemented. An acquired image was evaluated by the DIC program. DIC method for displacement and strain was suggests and it results show a good consistent remarkably. DIC results demonstrated the usefulness and ability to determine surface strain was better than by using classical measurements. The strain field measurement using a DIC is so useful that it can be applied to map strain distributions at a full area. DIC method can evaluate a strain change so it can predict a location of fracture. The findings of the investigation suggest that the DIC method is an efficient and reliable tool for full-field monitoring and detailed damage characterization of materials.

• Elastomers and Composites
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• v.44 no.4
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• pp.455-465
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• 2009

In this study, Organo-montmorillonite(MMT) was synthesized by intercalation of various amine(Octylamine, Dodecylamine, Dimethyldodecylamine, Octadecylamine) compounds into layered silicate. Natural Rubber(NR)/MMT nanocomposites were prepared by reinforcement of Organo-MMT. X-ray diffraction(XRD) and Scanning electron microscope(SEM) were employed to characterize the layer distance of Organo-MMT and the morphology of the NR/MMT nanocomposites. The structures of the synthesized Organo-MMTs were analyzed by the measurement of FT-IR. Cure characteristics, surface free energy and mechanical properties such as tensile strength, modulus and hardness of NR/MMT nanocomposites were carefully studied by contact angle meter, ODR, UTM, and hardness tester. FT-IR analysis showed a insertion of the alkyl and amine chains into the interlayers of the MMT. It was shown that the cure time of the organo-MMT was more decreased than that of $Na^+$-MMT. Surface free energy and tensile strength of the NR/DDA-MMT nanocomposite were the highest. NR/ODA-MMT nanocomposite was the highest in hardness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.174-180
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• 2019

In this study, we evaluated and analyzed the properties of polymeric transparent films used in military vehicle covers according to weathering test. Two types of polymer films (Film A and Film B) that are mostly used for military vehicle covers were selected. The weathering treatment condition and tester are described in KS K 0706, and the following weathering times were tested: 0hour, 40hours, 160hours and 320 hours. The tensile strength, elongation and thermal decomposition behavior and optical characteristics were analyzed. The tensile strength tended to decrease - increase - decrease with increasing weathering treatment time in both transparent films. The thermal decomposition temperature gradually decreased. Regarding the optical property, the light transmittance decreased and the haze tended to increase. However, film A showed almost similar optical characteristics after 160-hour weathering treatment.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.185-191
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• 2021

The characteristics of the foundry sand were analyzed for water jacket core required to prevent structural deformation from the heat generated in the cylinder bore during the casting of the cylinder block of an automobile. The sand core tensile strength tester, AFS-GFN, and optical microscope were used to evaluate the its properties. If the SiO2 content is high in the foundry sand, the dimensional defects and veining defects occur due to high temperature expansion. Also, if it is too low, the core breakage, porosities, chemical burn-on defects occur. The particle size index and grain shape influenced the core strength and resin consumption, resulting in fluctuations in defect types. The higher the alkalinity of the dried sand, the lower the core strength. And the more basic, the lower the core strength. At the resin content of 1.6~1.8%, the increase in core strength after 1 hour curing was approximately at its maximum.

• Journal of the Korean Chemical Society
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• v.58 no.3
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• pp.251-257
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• 2014

The stress relaxation of poly(methyl acrylate)-poly(acrylonitrile) copolymer samples were carried out in air and distilled water at various temperatures using the tensile tester with the solvent chamber. The rheological parameters were obtained by applying the experimental stress relaxation curves to the theoretical equation of the Eyring-Halsey non-Newtonian model. The self diffusion, hole volume, viscosities, and thermodynamic parameters of copolymer samples were calculated from rheological parameters and crystallite size in order to study of flow segments in amorphous region. It was observed that the rheological parameters of these copolymer samples are directly related to the self diffusion, hole volume, viscosities, and thermodynamic parameters of flow segments.

• Fibers and Polymers
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• v.3 no.1
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• pp.38-42
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• 2002

Polypropylene filaments were spun from a mixture of PP chips of two different Melt Flow Index (MFI) (3 MFI and 35 MFI). A significant difference was observed in the melting characteristics of the resultant filaments from either of the individual components as observed from the DSC. The main difference being in the degree of melting achieved at any temperature in the initial stages of the melting range, which was found to be higher in case of the filaments spun from the b]end. These filaments were then thermally bonded using silicon oil bath and heated roller method. Subsequently the bond strength of the filaments was measured on the Instron Tensile Tester using the loop technique. The values of the world strengths obtained from the blend were compared with those made from the individual component. It was found that the bond strength of the bonds obtained from the blended filament at a given temperature was higher than that of the bonds made from the filaments of either of the individual components, which is also suggested by the DSC curves. The difference in the bond strength was found to be as high as 25% in case of the blend with 60:40 composition ratios of the 3 MFI and 35 MFI components respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.5
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• pp.482-490
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• 1997

The effects of strain amplitude. test temperature and stress on the fatigue properties for Ti-Ni wires were investigated using a rotary bending fatigue tester specially designed for wires. The fatigue test results were discussed in connection with the static tensile properties. The DSC measurement was conducted after fatigue test in order to clarify the change of transformation behavior due to the progress of fatigue. Under the temperature below or near the Af, the strain amplitude($\varepsilon_a$)-failure life (Nf) curve showed to be composed of three straight lines with two turning points. Of the 2 turning points, the upper one was coincident with the elastic limit strain and the lower one with the proportional limit strain. With rising of the test temperature above Af, the pattern of $\varepsilon_a$-Nf curve changed gradually to composition of 2 straight lines. The $\varepsilon_a$-Nf curve shifted depending on test temperature. In the short and medium life zones, the higher the temperature was, the shorter the fatigue life. However, in the long life zone, above the Af temperature, the fatigue life was not affected by the temperature. The transformation enthalpy measured after fatigue test was dependent on Nf, $\varepsilon_a$, and test temperature.