• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.5
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• pp.430-435
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• 2007

This paper describes the results of electrical characteristics assessment for organic insulations of polyethylene(PE) series insulations and acrylonitrile butadiene styrene copolymer(ABS). In the experiment, 4 kinds of specimens by composition density were tested in relative permittivity, specific resistance and tracking duration. A WinDETA system and a tracking test set manufactured for this assessment were used to measure the dielectric parameters and tracking duration, respectively. In measuring the tracking duration, the time from testing voltage application to testing circuit breaking due to the tracking current was measured. As a result, dielectric dispersion was observed in measuring the relative permittivity of ABS. It was confirmed that the relative permittivity decreased with the density of the PE series insulations and it depends rather on the temperature than frequency. In most specimens, specific resistance exponentially decreased with frequency and the result for each specimen was almost similar. By the way, in the tracking test, all the PE series insulations showed more excellent performance than ABS and especially in the case of HDPE, its tracking withstand performance was the best.

• Computers and Concrete
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• v.30 no.5
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• pp.339-355
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• 2022

The high cost of ultra-high-performance engineered cementitious composite (UHP-ECC) is currently a crucial issue, especially in terms of the polyethylene (PE) fibers use. In this paper, cheap calcium carbonate whiskers (CW) were evaluated on the feasibility of hybrid with PE fibers. Diverse combinations of PE fibers and CW were employed to investigate the multi-scale enhancement on the UHP-ECC performance. A probabilistic-based UHP-ECC tensile strain reliability analysis approach was utilized, which was in general agreement with the experimental results. Furthermore, a multi-dimensional integrated representation was conducted for the comprehensive assessment of UHP-ECC. Results illustrated that CW improved the compressive strength and energy dissipation capacity of UHP-ECC owing to the microscopic strengthening mechanism. CW and PE fiber further promoted the saturated cracking of composite by multi-scale crack arresting effect. In particular, PE1.75-CW0.5 specimen possessed the best overall performance. The ultimate cracking width of PE1.75-CW0.5 group had 98 ㎛, which was 46.18% lower compared to PE2-CW0 group, the 28d compressive strength were slightly improved, the tensile strain capacity was comparable to that of PE2-CW0 group. The results above demonstrated that combinations of PE fiber and CW could significantly enhance the comprehensive performance of UHP-ECC, which was beneficial for large-scale engineering applications.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.79-85
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• 2007

An internal ballistic model to predict the performance of a Polyethylene-GOX (PE-GOX) hybrid motor was proposed and evaluated. A theoretical treatment of the model was followed by detail discussion of each of the factors affecting the overall performance. The present model consists of the governing equations by considering the unsteady burn-back rate of the fuel grain and on-off response characteristics of a oxygen-supply valve. The numerical results using the 4th order Runge-Kutta scheme with temporal physicochemical properties showed good agreements with test results and the global effects of the performance parameters, such as the burning area of the fuel grain, O/F ratio, and etc., on the performance of the motor were analyzed.

• Composites Research
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• v.12 no.2
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• pp.91-100
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• 1999

The manufacture of high strength polyethylene(HSPE) tape yarns has been accomplished by a solid state processing(SSP) method as the compaction of ultra-high molecular weight polyethylene(UHMWPE) powders and drawing of the compacted film under the melting point without any organic solvents. In this study, the characteristics of HSPE tape yarns produced by SSP which is desirable for production cost and environmental aspect were analyzed. As the results, tensile strengths of HSPE tape yarns increased with increasing the draw ratio and the fracture morphology of highly drawn HSPE tape yarns showed more fibrillar shape than the low drawn one. Interfacial shear strengths of HSPE tape yarns with vinylester resin increased by $O_2$ plasma treatment and maximum interfacial shear strength was obtained in the plasma treatment condition of 100W and 5min. In addition, mechanical properties of HSPE tape yarn reinforced composites were investigated and compared with those of the gel spun HSPE fiber reinforced composites.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.435-438
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• 1991

This work is aimed to clarify the effect of only crosslinking of polyethylene on the water tree propagation and thus the crosslinking of LDPE was made by use of $Co^{60}$ $\gamma$-ray irradiation at room temperature. For this purpose, before water tree testing under same test conditions, injection molded samples were made of LDPE using CNRS laboratory model and also some of them were irradiated under different dose rate for crosslinking. Afterwards, the aged specimens were put into microscopic investigation as a mean to compare their different morphological aspects by use of SEM for the fractured surface. The SEM observation points out that the untreed region in the irradiated PE shows the densed structure whereas that in the LDPE is not closely packed. Also in the water treed region of LDPE, the density and the dimension of voids are higher than those in irradiated PE. Based on our results, it seems that the difference in the PE structure could sufficiently contribute to cause the different water tree propagation of these materials.

• Textile Coloration and Finishing
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• v.32 no.4
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• pp.239-244
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• 2020

Polyethylene (PE) micro-fiber have been prepared at different hot air temperature (60, 80 and 100 ℃) and different pressure (20, 40, 60 and 80 kPa) by melt centrifugal spinning technique. The parameters of melting centrifugal spinning including polymer contents, rotational velocity, temperature of hot air and pressure were optimized for the fabrication process. The study showed that 8000 rpm rotational velocity, 80 ℃ heated hot air and 40 kPa air pressure are the best condition to obtain uniform and strong PE fiber. The prepared PE fibers were analyzed by field emission scanning electron microscope and universal testing machine and found that fibers with reduced diameter and improved tensile strength are obtained at hot air condition.

• Structural Engineering and Mechanics
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• v.74 no.5
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• pp.601-609
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• 2020

In this article, the Strain Energy Density (SED) averaged over a well-defined control volume at a notch edge was applied in combination with the Equivalent Material Concept (EMC) to assess the fracture behaviors of some keyhole-notched specimens made of a High-Density Polyethylene (HDPE-PE80) material under mixed-mode loading conditions. An experimental program was performed and 54 new experimental data were totally provided. Additionally, different loading mode ratios were regarded by changing the inclination angles of the notches with respect to the applied load directions. The results obtained from the determined criteria were in good agreement with those of the experimental data.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2000.04a
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• pp.139-141
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• 2000

Carboxylic acid group was introduced onto polyethylene (PE) film by the grafting of acrylic acid onto PE film irradiated with electron beam. The grafting Condition such as reaction temperature, additives, total irradiation dose, thickness of PE film, and monomer concentration was examined. The extent of grafting was found to increase with increasing reaction temperature and total irradiation dose. The grafting yield was much enhanced with the addition of both FeSO$_4$ 7H$_2$O and H$_2$SO$_4$.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.1036-1043
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• 1994

The silane crosslinking method was applied for the crosslinking of polyethylene (PE). Crosslinking of PE was performed by, first grafting vinyltrimethoxysilane(VTMOS) to the main chain of PE using an extruder at $200{\sim}210^{\circ}C$, followed by exposure to three different silane crosslinking conditions (1. immersed in $80^{\circ}C$ water, 2. at $80^{\circ}C$ air forced convection oven, 3. exposed to air at room temperature ). The thermal characteristic changes of PE resins with respect to the silane crosslinking conditions were studied by measuring the crystalline melting temperature, density and crosslinking reaction rate. Because silane crosslinking was carried out at solid state, crystalline melting temperature, crystallinity, crystal growth rate, crosslinking reaction rate and the change in the density of silane crosslinked PE were affected by crosslinking condition and the type of base resin. The properties of silane crosslinked PE were different from those of Peroxide crosslinked PE which was crosslinked at the molten state. It was found, from the result of DSC analysis, that silane crosslinked linear low density polyethylene(LLDPE) crosslinked at room temperature had no secondary melting peak because the crosslinking reaction proceeds slowly as the crystalline grows. After crystallization, the melting point of PE was lowered by crystalline interruption of crosslinked site.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.115-119
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• 1995

Electrical conduction characteristics of Polyethylene/Ethylene vinyl acetate blends of varing vinyl acetate content(1% and 4%) were investigated at electric fields ranging from 10$\^$6/ to 10.$\^$8/ V/cm over the temperature range of 30 and 85$^{\circ}C$. It was obser-ved that the extent of current density was changed at the blends and the rate of change of current den-sity was slightly suppressed at high field range, but PE and EVA were not shown. The change of con-duction characteristics and a suppression in rate of change of current density were attributed to the VA content in PE.EVA blends.