• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.69-78
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• 2007

The mechanical properties of wood flour, Hwangto (325 and 1,400 mesh per 25,4 mm) and coupling agent-reinforced HDPE composites were investigated in this study. Hwangto and maleated polyethylene (MAPE) were used as an inorganic filler and a coupling agent, respectively. The addition of Hwangto and MAPE to virgin HDPE also increased the Young's modulus in the smaller degree. The addition of wood flour and Hwangto to virgin HDPE increased the tensile strength, due to the high uniform dispersion of HDPE by high surface area of Hwangto in HDPE and wood flour. MAPE also significantly increased the tensile strength. When wood flour was added, there was no notable difference on the tensile properties, in terms of Hwangto particle size. Hwangto also improved the flexural modulus and strength of reinforced HDPE composites. With different particle sizes of Hwangto, there was no considerable difference in flexural modulus and strength of reinforced HDPE composites. The addition of Hwangto showed slightly lower impact strength than that of wood flour. However, the particle size of Hwangto showed no significant effect on the impact strength of reinforced composites. In conclusion, reinforced HDPE composites with organic and inorganic fillers provide highly improved mechanical properties over virgin HDPE.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.5-12
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• 2006

Degradation performance of environmentally friendly plastics that can be disintegrated by combination of sunlight, microbes in soil, and heat produced in landfills was evaluated for use in industries. Two multi-degradable master batches (MCC-101 and MCC-102 were manufactured, separately mixed with polyethylene using film molding machine to produce 0.025 mm thick films, and exposed to sunlight, microbes, and heat. Low- and high-density polyethylene (LDPE and HDPE) films containing MCC-101 and MCC-102 became unfunctional by increasing severe cleavage at the surface and showed high reduction in elongation after 40 days of exposure to ultraviolet light. LDPE and HDPE films showed significant physical degradation after 100 and 120 days, respectively, of incubation at $68{\pm}2^{\circ}C$. SEM images of films cultured in mixed mold spore suspension at $30^{\circ}C$ and 85% humidity for 30 days revealed accelerated biodegradation on film surfaces by the action of microbes. LDPE films containing MCC-l01 showed absorption of carbonyls, photo-sensitive sites, at $1710\;cm${-1}$ when exposed to light for 40 days, whereas those not exposed to ultraviolet light showed no absorption at the same frequency. MCC-101-based LDPE films showed much lower $M_w$ distribution after exposure to UV than its counterpart, due to agents accelerating photo-degradation contained in MCC-101.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.106-108
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• 1997

In this paper, the breakdown strength of Pure HDPE(High density polyethylene) films and aged HDPE films were evaluated using 2-parameter Weibull distribution function. The result show that both were fitted 2-parameter Weibull distribution. This method could be used to be the diagnostic tool to evalute the insulation performance and endurance under the multiple stresses.

• Journal of Radiation Protection and Research
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• v.34 no.1
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• pp.9-14
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• 2009

High density polyethylene (HDPE) is degraded due to a radiation-induced oxidation when it is used as a neutron moderator in a neutron counter for a nuclear material accounting of spent fuels. The HDPE exposed to the gamma-ray emitted from the fission products in a spent nuclear fuel results in a radiation-induced degradation which changes its original molecular structure to others. So a neutron moderating power variation of HDPE, irradiated by a gamma radiation, was investigated in this work. Five HDPE moderator structures were exposed to the gamma radiation emitted from a $^{60}Co$ source to a level of $10^5-10^9$ rad to compare their post-irradiation properties. As a result of the neutron measurement test with 5 irradiated HDPE structures and a neutron measuring system, it was confirmed that the neutron moderating power for the $10^5$ rad irradiated HDPE moderator revealed the largest decrease when the un-irradiated pure one was used as a reference. It implies that a neutron moderating power variation of HDPE is not directly proportional to the integrated gamma dose rate. To clarify the cause of these changes, some techniques such as a FTIR, an element analysis and a densitometry were employed. As a result of these analyses, it was confirmed that the molecular structure of the gamma irradiated HDPEs had partially changed to others, and the contents of hydrogen and oxygen had varied during the process of a radiation-induced degradation. The mechanism of these changes cannot be explained in detail at present, and thus need further study.

• 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.

• 전기의세계
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• v.27 no.3
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• pp.31-35
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• 1978

In this paper, in order to clarify the mature of traps in polymer, the thermally stimulated current (TSC) measurements were mad on high density polyethylene by changing the condition of the high-field treatment such as the strength of the field (Fe), the treatment time (te) and the heating rate (.betha.). In addition, the TSC measured from the HDPE was compared with that from LDPE having different crystallinity. The obtained results can suggest that the trapping proceeds during the high-field treatment and the trap associated with the peak P$_{2}$ may have the closed relation to drystallinity and the release of trapped charge is enhanced by the molecular motion.

• Fire Science and Engineering
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• v.27 no.6
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• pp.44-49
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• 2013

As the polyethylene of high strength and ductility stabilized chemically has been mass-produced, it is spreading widely as material of industrial piping and water service piping. Recently, High density polyethylene (HDPE) pipe has been used even in water supply system of plant as buried pipe instead of cast iron pipe in domestic, but HDPE pipe has a probability of occurrence of damage if plant design and operating conditions are not considered. As a result of reviewing with respect of system design engineering based on operating conditions and verification test results, the specific design criteria for the use of HDPE piping in fire water supply system need to be established because of the possibility of crack damage due to water hammer.

• Journal of the Korean Wood Science and Technology
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• v.34 no.5
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• pp.59-66
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• 2006

The thermal properties of wood flour, Hwangto, and maleated polyethylene (MAPE) reinforced HDPE composites were investigated in this study. The thermal behavior of reinforced wood polymer composites was characterized by means of thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses. Hwangto and MAPE were used as an inorganic filler and a coupling agent, respectively. According to TGA analysis, the increase of wood flour level increased the thermal degradation of composites in the early stage, but decreased in the late stage. On the other hand, Hwangto reinforced composites showed the higher thermal stability than virgin HDPE, from the determination of differential peak temperature ($DT_p$). Decomposition temperature of wood flour and/or Hwangto reinforced composites increased with increase of heating rate. From DSC analysis, melting temperature of reinforced composites little bit increased with the addition of wood flour or Hwangto. As the loading of wood flour or Hwangto to HDPE increased, overall enthalpy decreased. It showed that wood flour and Hwangto absorbed more heat energy for melting the reinforced composites. Hwangto reinforced composites required more heat energy than wood flour reinforced composites and virgin HDPE. Coupling agent gave no significant effect on the thermal properties of composites. Thermal analyses indicate that composites with Hwangto are more thermally stable than those without Hwangto.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.270-275
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• 2016

High density polyethylene (HDPE)/kenaf fiber (KF) composites included two types of KF with different lengths were fabricated by using a twin screw extruder. A thermally expandable microcapsule (EMC) was used to form HDPE/KF. The KF lengths were 0.3 mm and 3 mm. The contents of KF and EMC were fixed at 20 wt% and 5 wt%, respectively. From FT-IR data of KF, which underwent chemical treatment, peaks around 1700 and $1300cm^{-1}$ decreased. This might be caused by the reduction of lignin and hemicellulose due to the chemical treatment of KF. Based on the specific gravity, thermal stability and tensile property, physical properties of the composites with a 3 mm fiber were good. However, if the fiber is longer, poor appearance might be caused due to the thermal degradation during processing. Thus, the adequate length of KF should be chosen to maintain the appearance and physical properties for industrial applications of HDPE/KF/EMC composites. The tensile strength for 0.3 mm fiber treated with chemicals increased slightly.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.344-350
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• 1999

The surface chemical structure of three kinds of polyethylene (PE): high density (HD) PE, low density (LD) PE and linear (L)-LDPE exposed to Ar and $O_2$ plasmas has been investigated using XPS. Oxygen was incorporated in a more increased amount for HDPE than for L-LDPE and LDPE. Ar plasma tended to incorporate more oxygen than $O_2$ plasma. The XPS valence band spectra for Ar plasma exhibited a clear peak assigned to $O_2$s character. By chemical derivatization method it was found that the amount of -COOH group at the surface was much greater than that of -OH group. The hydrophilic nature of plasma-treated PE increased in the order: LDPE