• 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.

• Elastomers and Composites
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• v.36 no.3
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• pp.188-194
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• 2001

Thermoplastic elastomers based on dynamically vulcanized NR/TOR/PP (rubber/PP=70/30) blends were prepared in a Haake banbury mixer. Effect of TOR content on the mechanical, dynamic mechanical and thermal stability of the rubber/plastic blends was characterized by UTM, DMTA, and TGA. On the addition of trans-polyoctylene rubber(TOR) to the rubber phase, there was a decrease in compression set and increase in tensile properties, hardness and dynamic properties as well as thermal stability or the elastomeric blends. Improvements in the properties were believed to be due to an increase in crosslink density of the rubber phase and increase in homogeneity of the blends.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1216-1221
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• 2014

Poly(ethylene-co-isosorbide terephthalate) (PEIT) is interest in polymer which has isosorbide monomer that is renewable resources such as corn. However, there is important drawback which is low mechnical properties as increasing isosorbide contents. In this study, polycarbonate used to make up for drawback of mechanical properties of PEIT. In addition, PEIT used to improve the tensile elongation of polycarbonate because PEIT has good sheet proccessability. The effect of polycarbonate on morphology, thermal and mechanical properties were investigated using FE-SEM, DMA, TGA, UTM, and notched izod impact strength tester. As a result of this study, PEIT/PC blends were in compatible system and polycarbonate can act as an improvement of thermal stability and mechanical properties in the blends.

• Polymer(Korea)
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• v.34 no.4
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• pp.326-332
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• 2010

Nanocomposite films were prepared by blending poly(amic acid)(PAA), poly(o-hydroxyamide)( PHA) and organically modified montmorillonite (OMMT) that has a layered structure. XRD, SEM and TEM were used to study the morphology of PAA/PHA nanocomposites, and DMA, TGA, UTM, LOI and PCFC techniques were used to characterize the mechanical and thermal properties, and flame retardancy of the nanocomposites. TEM images revealed that OMMT layers were well dispersed in the PAA/PHA matrix and showed exfoliation and intercalation behavior. The addition of 3 wt% OMMT to the PAA/PHA blend increased the initial modulus of PAA/ PHA blend to 3.68 GPa that was ca. 48% higher than that of the control PAA/PHA blend. Above 4 wt%, however, both the initial modulus and the tensile strength were found to decrease, which might be due to the aggregation of OMMT in PAA/PHA matrix. When the OMMT content was below 3 wt%, the thermal stability and flame retardancy of the PAA/PHA nanocomposites increased with increasing OMMT content.

• Clean Technology
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• v.21 no.1
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• pp.76-82
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• 2015

Volatile organic compounds (VOC) free adhesives have been interested by many scientists and engineers due to environmental regulations and the safety of industrial workers. In this work, a series of composites composed with bisphenol A epoxy resin used as solvent, dicyandiamide, and promoter were prepared to investigate the most appropriate molar ratio for steel-steel adhesion. The cured test specimen of each composite were measured with universal testing machine (UTM) to figure out mechanical properties such as tensile strength, Young’s modulus, and elongation. Furthermore, the lap shear strength of the specimen was tested with UTM while impact resistance was measured with Izod impact tester. The composite whose molar ratio of epoxy resin to curing agent is 1 : 0.9 (sample 3), showed better tensile strength, coefficient of elastic modulus, elongation, and impact strength than other composites did. The highest tanδ from dynamic mechanical analysis (DMA) was observed from sample 2 (epoxy resin: dicy = 1 : 0.7) while sample 3 showed slightly lower tanδ than that of 2. The morphology of the fracture surface of the cured composites from SEM showed that the number of subtle lines on the surface caused by impact increase as the contents of amine curing agent accrete. Furthermore, the viscosity change of sample 5 (epoxy resin: dicy = 1 : 1.3) was observed to confirm its storage stability.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.583-590
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• 2015

Submarine cable installation is essentials for grid connection between existing power grid and newly produced electricity which will be from offshore wind farm in Southwest sea area of Korea. Especially, submarine cable route and protection method is designed in order to ensure the economical efficiency, workability and stability of submarine cable installation. On this paper, we will give the basic information about the submarine cable route and protection method of offshore wind farm which will be built in Southwest sea area of Korea. For this, we have a numerical simulation at high and low tide based on the third-generation wave model SWAN(Simulating WAves Nearshore) using the long term wave data from Korea Institute of Ocean Science and Technology(KIOST). The results of the study, year mean Hs is 1.03m, Tz is 4.47s and dominant wave direction is NW and SSW When the incident wave direction is NW(Hs: 7.0 m, Tp: 11.76s), the distribution of shallow water design wave height Hs was calculated about 4.0~5.0m at high tide and 2.0~3.0m at low tide. When the incident wave direction is SSW(Hs: 5.84 m, Tp: 11.15s), the distribution of shallow water design wave height Hs was calculated about 3.5~4.5m at high tide and 1.5~2.5m at low tide. The wave direction on a dominant influence in the section of longitude UTM 249749~251349(about 1.6 km) and UTM 251549~267749(about 16.2 km) in the submarine cable route are each NW and SSW. Prominently, wave focusing phenomenon appears between Wi-do and Hawangdeung-do, in this sea area is showing a relatively high wave hight than the surrounding sea areas.

• Polymer(Korea)
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• v.34 no.6
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• pp.495-500
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• 2010

Crosslinked PI films were synthesized from 4,4'-(hexafluoro isopropylidene)diphthalic anhydride (6FDA) and bis[4-(3-aminophenoxy) phenyl] sulfone(BAPS) with various ratios of the reactive monomer cis-4-cyclohexene-1,2-dicarboxylic anhydride(CDBA). We prepared crosslinked poly(amic acid) (PAA) using a 0.1 wt% Grubbs catalyst as a crosslinking agent. The crosslinked PAA was heat-treated at different temperatures to give PI films. The thermo-mechanical properties and optical transparency of the PI films were investigated. The thermal properties of the PI films were examined using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry(DSC), thermogravimetric analysis(TGA), thermo-mechanical analysis(TMA), and universal tensile machine(UTM), and their optical transparencies were investigated using UV-vis. spectrophotometry. The thermomechanical properties of the PI films improved with increasing CDBA content. However, the optical transparency of the PI films decreased slightly with increasing CDBA content.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.1
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• pp.1-7
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• 2003

The carbon composite tube can play an important role in replacing or complementing longitudinal and transverse reinforcing steels by providing ductility and strength for conventional columns. In this study, both the experimental and analytical investigations of axial behavior of large-scale square concrete columns confined by carbon composite tube are presented. The specimens are filament-wound carbon composite with 90$^{\circ}$+30$^{\circ}$, 90$^{\circ}$+45$^{\circ}$ winding angle respect to longitudinal axis of tube. The instrumented large-scale concrete-filled composite tubes(CFCT) are subjected to monotonic axial loads exerted by 10,000kN UTM. The influence of winding angle, thickness of tube on stress-strain relationships of the confined columns is identified and discussed. Proposed equations to predict both the strength and ductility of confined columns by carbon composite tube demonstrate good correlation with test data obtained from large-scale specimens.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.266-270
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• 2012

A series of polyimide was prepared by reacting 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) as the anhydride monomer and 2,2'-bis(trifluoromethyl)benzidine (TFB), 2,2'-bis(3-aminophenyl)hexafluoropropane (BAFP), 2,2'-bis(3- amino- 4-methylphenyl) hexafluoropropane (BAMF), bis(3-aminophenyl)sulfone (APS), p-xylyenediamine (p-XDA), or m-xylyenediamine (m-XDA) as the amine monomer in N,N-dimethylacetamide (DMAc). Colorless and transparent polyimide (PI) films were obtained by casting the poly(amic acid)s (PAAs) solution at various heat treatment temperatures. The thermal properties of the PI films were examined using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermomechanical analysis (TMA) and the mechanical properties were investigated using universal tensile machine (UTM), Their optical transparencies were also investigated using ultraviolet-visible (UV-vis.) spectrophotometry and colorimetry. The yellow index (YI) and coefficient of thermal expansion (CTE) values of all PIs were in the range 0.98~2.76 and 25.73~55.23 $ppm/^{\circ}C$, respectively.

• Polymer(Korea)
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• v.35 no.2
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• pp.124-129
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• 2011

Wood plastic composites (WPCs) are attracting a lot of interest recently. In this study, wood flour/polyethylene (PE) composites panels comprised of a coupling agent and nanoclay were prepared by melt-blending followed by compression molding. Five maleic anhydride grafted polyethylene (MAPE) coupling agents were tested, and the best choice and its optimum content were determined. The mechanical properties of the WPCs were measured by UTM, and the thermal properties were measured by TGA, DMA, DSC, and TMA. Adding just a small amount (1 phr) of organoclay made the tensile and flexural strength and the crystallinity of the WPC somewhat increase and the storage modulus and dimensional stability of the WPC largely increase. SEM images showed that the coupling agent drastically improved wood flour/PE interfacial bonding. Selecting the best coupling agent optimized content and adding a small amount of organoclay resulted in a high performance wood flour/PE composite.