• Journal of Korean Ophthalmic Optics Society
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• v.12 no.1
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• pp.41-51
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• 2007

Differential equations and their solutions were formulated to describe the deflection of the tapered, nonuniform thickness and width's temple, clamped at one end while the perpendicular force is acting on the other end which is freely suspended. The model was derived based on laws of continuity at every point inside the elastic medium that the deflection, tangent slope, bending moment, shearing force must be continuous within the medium. The model is found to be in good agreement with measurements on the beta titanium temple with the correlation 0.992 and p=0.999(Chi test). Therefore it is possible to predict the effect of various temple parameters such as elastic modulus, thickness, width on the deflection of the temples being considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.367-371
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• 2007

Nanocomposites prepared by PP(Polypropylene) based compatibilizers modified with GMA(Glycidyl methacrylate) and HEMA(Hydroxyethyl methacrylate) were used to investigate the clay dispersion and mechanical properties of them. XRD patterns showed the improvement of dispersion through clay intercalation according to the compatibilizers and comonomer. GMA modified polypropylene gave the best mechanical properties of the nanocomposite with respect to the balance of Flexural modulus (FM) and Notched izod impact strength(IS). Compatibilizers with comonoer commonly have higher grafting yield and lower melt flow rate than those of comonomer free. And they enhanced the clay dispersion and mechanical properties of nanocomposites. Optimum ratio of monomer to comonomer for nanocomposites having better mechanical properties is about 1 to 1 ratio.

• Elastomers and Composites
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• v.46 no.2
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• pp.125-131
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• 2011

The effects of chopped kenaf fiber concentration on mechanical property of polypropylene (PP) composite are investigated. The addition of kenaf increased the tensile strength, flexural modulus, impact strength, specific gravity, and HDT, while decreased the elongation%, flexural strength, and melt flow index. The increase of mechanical properties is due to increased surface area contacting between fiber and polymer matrix and fiber-fiber interaction. Volatile extractives in the kenaf seemed to decrease the interfacial adhesion between kenaf surface and PP.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.935-942
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• 1994

Two types of ABS were prepared from diffrent types of rubber, and blends of the ABS and PMMA were compounded and evaluated in terms of morphology, mechaincal and rheological properties. In addition, the effect of carbon black in the ABS/PMMA blends were studied. With increasing PMMA content, flexural modulus, tensile yield strength, and surface gloss of the blends increased, but elongation at break and Izod Impact strength decreased. With carbon black addition, mechanical properties were generally decreased. Effects of the type of ABS, and carbon black on melt properties were also studied.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.491-497
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• 2010

In this paper, we employed the classical molecular dynamics simulations using Tersoff's potential to calculate the elastic constants of the silicon carbide (SiC) crystal at high temperature. The elastic constants of the SiC crystal were calculated based on the stress-strain characteristics, which were drawn by the simulation using LAMMPS software. At the same time, the elastic constants of the SiC ceramics were measured at different temperatures by impulse excitation testing (IET) method. Based on the simulated stress-strain results, the SiC crystal showed the elastic deformation characteristics at the low temperature region, while a slight plastic deformation behavior was observed at high strain over $1,000^{\circ}C$ temperature. The elastic constants of the SiC crystal were changed from about 475 GPa to 425 GPa by increasing the temperature from RT to $1,250^{\circ}C$. When compared to the experimental values of the SiC ceramics, the simulation results, which are unable to obtain by experiments, are found to be very useful to predict the stress-strain behaviors and the elastic constant of the ceramics at high temperature.

• Journal of Adhesion and Interface
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• v.14 no.4
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• pp.167-174
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• 2013

In this study, Ultraviolet (UV) curable urethane acrylates for ink binder was prepared by reaction of IPDI, polyether polyol and HEA. The UV curing behavior of compositions with HEA/PETA ratio on UV irradiation time was investigated by FT-IR spectrophotometer, probe tack tester and Photo-DSC. Conversion % and gel content were increased with increasing UV irradiation time, but probe tack was decreased. Storage modulus, tensile strength and decomposition temperature were increased as PETA content increased. In case of HEA/PETA ratio was 30/70, adhesion property of UV-cured composition on PMMA sheet was excellent.

• Fire Science and Engineering
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• v.16 no.4
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• pp.65-71
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• 2002

In this paper, the thermal and flame properties of GFRP with various flame retardant(aluminum trihydrate, antimony trioxide) compositions have been investigated by thermal analysis and flammability tests(LOI test, flammability 45 degree test). The flame and mechanical properties(hardness, tensile strength, modulus) of general purpose grade glass fiber/unsaturated polyester composite with flame retardant composition have been also evaluated. The effect of cure pressure on the flame properties of aerospace grade glass fiber/epoxy composite was investigated. Considering the flame and mechanical property of composite, we could determine the optimum flame retardant composition(ATH 10∼20 phr). Test results show that the flame property of glass fiber/epoxy composite is considerably affected by cure pressure conditions.

• Polymer(Korea)
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• v.25 no.2
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• pp.208-217
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• 2001

PET/BPA copolymer of terephthalic acid, bisphenol-A and ethylene glycol was melt-pressed and quenched in ice water. This copolymer film was drawn by capillary rheometer. Shrinkage, crystallinity, morphology, thermal, dynamic mechanical, and mechanical properties of these copolymer films were investigated. The PET/BPA copolymer film exhibited T$_{m}$ lower than that of PET film. The crystallinity and density of these drawn copolymer films increased with draw ratio and draw rate but decreased with draw temperature. The tensile strength and tensile modulus of the copolymer films increased with draw ratio but decreased with draw temperature. Shrinkage of the drawn copolymer film decreased with draw ratio and draw rate.e.

• Polymer(Korea)
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• v.28 no.6
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• pp.519-523
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• 2004

Starch was grafted with maleic anhydride by melt process and then the grafted starch was blended with poly(lactic acid). The thermal properties of the poly(lactic acid), poly(lactic acid)/starch, and poly(lactic acid)/ modified starch were observed by DSC and TGA analysis. In the case of poly(lactic acid)/modified starch, an additional melting peak at 1$65^{\circ}C$ accompanying with 172$^{\circ}C$ assigned to pure poly(lactic acid) melting transition was clearly displayed in DSC analysis. Also, smooth decomposition pattern between starch and poly(lactic acid) was also monitored in poly(lactic acid)/modified starch blend by TGA analysis. The modulus of poly(lactic acid)/modified starch was 12％ higher than that of poly(lactic acid)/starch. The thermal and mechanical characteristics of poly(lactic acid)/modified starch might be due to the enhanced compatibilization between each components, which was also observed in SEM analysis.

• Polymer(Korea)
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• v.30 no.6
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• pp.532-537
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• 2006

In order to successfully meet the environmental and recycling problems, natural polymer and their derivatives are recognized as a promising biodegradable material. In this study, the biodegradable composites of cellulose diacetate and starch were prepared, and their physical and thermal properties were investigated. For the melting processing, triacetine was added as a plasticizer into the composites. The processability of cellulose diacetate was further enhanced by increasing the amount of starch in the composites. The tensile stress and Young's modulus were decreased and elongation was increased with increasing the amount of starch in them. A $T_g$ value was decreased with increasing the amount of starch in the composites. Also, the morphology of the composites were observed with the SEM.