• Polymer(Korea)
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• v.38 no.1
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• pp.62-68
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• 2014

To improve the compatibility of bentonite with rubber matrix, organo-modified bentonite was synthesized with a silane coupling agent, [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAPTMS) in the suspension of bentonite. The structure and characteristics of organo-modified bentonite were investigated using FTIR-spectroscopy, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Ethylene-propylene-diene monomer (EPDM) rubber/organo-bentonite composites were compounded by a two-roll mill. The vulcanization and mechanical properties were studied. Results showed that the concentration of hydrochloric acid and $H_2O$ in the synthesis had significant influence on the modification of bentonite, which further contributed to the properties of the composites. Filled with 20 phr modified bentonite, the tensile strength and elongation at break of the rubber increased from 1.95 to 4.8 MPa and 300% to 500%, respectively.

• Journal of the Korea Society of Computer and Information
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• v.26 no.2
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• pp.53-60
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• 2021

In this paper, we aimed to identify the insulation characteristics and reliability of Epoxy composites, which are widely used as insulation material for electrical & electronic components and electric appliance. To this end, it was necessary to predict variations of electric field due to the distribution of fillers that must be added by economic and mechanical factors. So, we verified the result using an electric field analysis Simulator. Furthermore, under the condtion of DC voltage application, an dielectirc breakdown test was performed according to ambient temperature changes and the distribution of fillers, and the changes were observed. Three types of specimens were manufactured by adding 0, 50 and 100[phr] filling to Epoxy resin. In all specimens, as temperature was increased, the strength of the dielectric strength was decreased. When comparing the simulation results with the actual dielectric breakdown test results, we was able to confirm the technical applicability required for Insulation design of electric appliance.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.349-354
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• 2022

This research was conducted in order to improve the hydrolysis resistance and mechanical properties of a resin compound and biodegradable mulching film, produced through the use of PBAT(Poly Butylene Adipate-co-Terephthalate) and PLA(Poly Lactic Acid). Various ratios of chain extenders and mechanical properties according to the annealing temperature conditions were investigated. The annealing process showed that compound resin can improve the crystallization capacity. In addition, incorporation of the chain extender was shown to improve and increase the tensile strength and hydrolysis resistance of the film. In the case of 0.6phr chain extender, the tensile strength was 383.0Kgf/cm², which was improved by 155% compared to the control films. When the blow up ratio(BUR) was 2.5, the optimal tensile strength of the film increased greatly, expanding up to 379.0/195.2kgf/cm² in the both machine direction (MD) and transverse direction (TD).

• Elastomers and Composites
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• v.56 no.4
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• pp.243-249
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• 2021

The demand for truck bus radial (TBR) tires with enhanced fuel efficiency and wear resistance have grown in recent years. In addition, as the issue of particulate matter and air pollution increases, efforts are being made to reduce the generation of particulate matter. In this study, we investigated the effect of varying the content of butadiene rubber (BR) on the properties of the rubber compounds and the amount of particulate matter in the TBR tire tread compound. Furthermore, we utilized carbon black in the NR/BR blend compounds owing to its excellent compatibility, and we used silica in the ENR-25/BR blend compounds because it can interact chemically with epoxide groups. The NR/BR blend compounds and the ENR-25/BR blend compounds were evaluated by varying their BR content between 20 phr and 30 phr. The results showed that the ENR-25/BR blend compounds had superior wear resistance than the NR/BR blend compounds. This was caused by the interaction between silica and ENR. In addition, it was confirmed that the increased wear resistance as the BR content increased. Furthermore, compared to the NR/BR blend compounds, ENR-25/BR blend compounds exhibited a lower tan 𝛿 value at 60℃ because silica was used as filler. This indicates a higher fuel efficiency. The measurement results for wear particulate matter showed that as increasing the BR content resulted in generation of less wear particulate matter. This was caused by the increased wear resistance. Moreover, the ENR-25/BR blend compounds with excellent filler-rubber interaction exhibited lower quantities of generated wear particulate matters as compared to the NR/BR blend compounds.

• Textile Coloration and Finishing
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• v.33 no.4
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• pp.317-326
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• 2021

In this study, we investigated for Bio-EPDM foam with oyster shell surface modified earth coupling agent. Experiments were carried out to confirm the bio-EPDM/Oyster shell foam applying content of earth coupling agent. The cure characterization were evaluated by measuring the mooney viscosity and oscillating disc rheometer (ODR). Mechanical properties such as hardness, tensile strength, elogation at break and tear strength were measured, and changes of mechanical properties were also evaluated after immersion in NaCl solution. In addition degree of volume change was measured after immersing the Bio-EPDM foam in NaCl solution and the low-temperature permanent compression set was evaluated at 4℃. To evaluate the low-temperature characteristics of Bio-EPDM/Oyster shell, the glass transition temperature was measured using Differential Scanning Calorimeter (DSC). As a result as the content of the earth coupling agent increased up to 3phr, the crosslinking density and mooney viscosity increased, and the mechanical properties and low-temperature permanent compression set improved, but from 4phr, it was rather decreased. The change in the glass transition temperature was insignificant, and the foam cell appeared to be uniform when the earth coupling agent was applied.

• Clean Technology
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• v.15 no.3
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• pp.180-185
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• 2009

The ethylene-propylene rubber (EPDM) scrap generated from automobile weatherstrip manufacturing process was used to make a thermoplastic elastomer through blending with polypropylene. The surface activated EPDM powder was obtained by the high temperature and shear pulverizer. The addition of surfactant resulted in more surface activated EPDM powder and the optimum loading amounts of surfactant was 1.5 phr. Maleic anhydride was grafted onto polypropylene by reactive blending to give functionalized polypropylene. The wetting property between EPDM scrap and polypropylene was improved by the addition of poly (ethylene-co-acrylic acid) as a compatibilizing agent. Poly(ethylene-co-acrylic acid) decreased the surface tension of polypropylene and thus would contribute to the wettability with EPDM powder.

• Clean Technology
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• v.16 no.4
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• pp.245-253
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• 2010

Optimum conditions for UV-radiated photopolymerization of unsaturated polyester that could be used as protecting layer of large diameter pipe were investigated in this paper. UV photopolymerization method was selected to solve the problems, arising when thermal polymerization by organic peroxide was used, such as the instability of peroxide initiator, the evolution of volatile organic compound, and thermal deformation of product. Two of the photo-initiators (Irgacure 819 and Darocure 1173) well known for its penetrating ability deep into the polymer layer were selected, and the optimum conditions for photopolymerization (1.5 phr initiator content, 1:1.2 initiator ratio, Ga lamp for UV source) were found from the thermal and mechanical test results of the resultant UP polymers. In addition, composite materials containing UP polymer and glass fiber were tested for hardness, impact strength, and flexural strength to find that the impact strength of composite significantly improved.

• The Journal of the Acoustical Society of Korea
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• v.28 no.5
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• pp.447-453
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• 2009

This paper introduces the method for detect voices and exact end point at low SNR by maximizing voice energy. Conventional VAD (Voice Activity Detection) algorithm estimates noise level so it tends to detect the end point inaccurately. Moreover, because it uses relatively long analysis range for reflecting temporal change of noise, computing load too high for application. In this paper, the SEM-VAD (Speech Energy Maximization-Voice Activity Detection) method which uses psycho-acoustical bark scale filter banks to maximize voice energy within frames is introduced. Stable threshold values are obtained at various noise environments (SNR 15 dB, 10 dB, 5 dB, 0 dB). At the test for voice detection in car noisy environment, PHR (Pause Hit Rate) was 100%accurate at every noise environment, and FAR (False Alarm Rate) shows 0% at SNR15 dB and 10 dB, 5.6% at SNR5 dB and 9.5% at SNR0 dB.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1578-1580
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• 1999

Silicone rubber is being used for the housing material of outdoor high voltage insulators such as composite insulator, bushing, surge arrestor and cable terminator because of good tracking and erosion resistance, good hydrophobicity and recovery of hydrophobicity, and chemical stability. In this paper, tracking and erosion resistance of silicone rubber having fluids and different ATH contents were examined. Fluids were selected under the consideration of their molecular weight and chemical structure, expecting the high migration rate, the good pollutant encapsulation, and the long period with good hydrophobicity. Good tracking and erosion resistance and arc resistance have been achieved for the silicone rubber above ATH content 130 phr.

• Elastomers and Composites
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• v.29 no.5
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• pp.431-435
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• 1994

For recycling of the waste tires, polyurethane binder mixed with the scrapped rubber powders which obtained from tread part of waste tire. This study covered the effect of the binder contents on the mechanical properties of the blend. We also studied the change of the properties after aging on properties compared with those of before aging. The curing reaction of the binder was also investigated in this study. We obtained conclusions the suitable binder content was 15phr in this system.