• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.35-36
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• 2003

The purpose of this work is to investigate the surface modification of LDPE film via corona discharge treatment and subsequent graft polymerization, and their effect on the resulting dyeability is studied in terms of the surface functional groups, surface energetics, and acid-base interaction between the modified LDPE and the dyes used.

• Food Science and Preservation
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• v.7 no.1
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• pp.33-37
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• 2000

Effects on keeping quality according to the different package environment in cabbage and brccoli were studied. Opened 2 mil LDPE (low density polyethylene) sealed 4 mil LDPE and BA(barrier polyethylene) were used as package films. Weight loss was markedly in opened 2 mil LDPE in cabbage and broccoli as 6 and 28%, respectively. Carbon dioxide was higher in seal-packaging cabbage and broccoli with BA held at 4 $^{\circ}C$ was above 15 and 31% within 15 days, respectively, while oxygen content was depleted to 2% or less after 10 days. The main difference between volatile sulfur-containing compounds produced from cabbage and broccoli were the relative quantities and rates of production of hydrogen sulfide, carbonyl sulfide, methanethiol and dimethyl disulfide in opened 2 mil LDPE , sealed 4 mil LDPE and barrier bags during storage.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.453-460
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• 1997

In order to investigate the electrical conduction properties of polyethylene thin film for power cable with manufacturing methods, the thickness of specimen was the 30, 100[${\mu}{\textrm}{m}$] of LDPE and 200[${\mu}{\textrm}{m}$] of XLPE were manufactured. The experimental condition for conduction properties was measured until the breakdown occurs at temperature ranges from 30 to 110[$^{\circ}C$] and the electric field from 1$\times$10$^3$to 5$\times$10$^{6}$ [V/cm]. As for increase of temperature, the current density of LDPE was increased with constant ratio in low field, but changes with exponential function in high electric field. The tunnel current of pre-breakdown region is shifted toward low field as much as thermal excitation energy. At low electric field, the XLPE showed dominant electrical conduction properties by thermal excitation, and transformation of the electron was resisted by the crystal at high electric field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.593-596
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• 2001

In the previous work, the effect of blending with two kinds of low density polyethylene (LDPE) on physical and electrical properties have been investigated. From the results, blending with two kinds of LDPE was effective method on changing the morphology of LDPE and improving the high-field characteristics in high temperature region. Especially, it suggested that the F$\_$BImp/ was associated with the changes of the crystal size. In this work, the relationship between the morphology and the high-field characteristics of blended LDPE was discussed. In addition, the physical and electrical properties of blended LDPE with extrusion treatment were investigated. The two groups of specimen were prepared; Group 1 was prepared by passing 1 time through the extruder included in the film-blowing process, and Group 2 was prepared by passing 2 times through the extruder. From the relation between the crystal size which was perpendicular to the (020) plane and the F$\_$BImp/ of blended LDPE, it was confirmed that the F$\_$BImp/ was associated with the changes of crystal size due to the blending. Moreover, the F$\_$BImp/ of blended LDPE in Group 2 was higher than that of blended LDPE in Group 1. The crystal size of the (020) plane became smaller according to the extrusion treatment. These results suggest that the uniform distribution and dispersion of crystalline occurred due to the extrusion treatment and the morphological change due to the extrusion treatment influenced on the electrical properties of blended LDPE.

• New & Renewable Energy
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• v.18 no.4
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• pp.12-21
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• 2022

The pyrolysis characteristics of high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) were analyzed numerically using a 1D plug flow reactor (PFR) model. A lumped kinetic model was selected to simplify the pyrolysis products as wax, oil, and gas. The simulation was performed in the 400-600℃ range, and the plastic pyrolysis and product generation characteristics with respect to time were compared at various temperatures. It was found that plastic pyrolysis accelerates rapidly as the temperature rises. The amounts of the pyrolysis products wax and oil increase and then decrease with time, whereas the amount of gas produced increases continuously. In LDPE pyrolysis, the pyrolysis time was longer than that observed for other plastics at a specified temperature, and the amount of wax generated was the greatest. The maximum mass fraction of oil was obtained in the order of HDPE, PP, and LDPE at a specified temperature, and it decreased with temperature. Although the 1D model adopted in this study has a limitation in that it does not include material transport and heat transfer phenomena, the qualitative results presented herein could provide base data regarding various types of plastic pyrolysis to predict the product characteristics. These results can in turn be used when designing pyrolysis reactors.

• Korean Journal of Materials Research
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• v.29 no.10
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• pp.603-608
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• 2019

Plastic waste is becoming a problem in various countries because of the difficulty of natural decomposition. One type is PET plastic(Polyethylene Terephthalate), which is often used as a bottle for soft drink packaging, and LDPE(Low Density Polyethylene), which is also widely used as a food or beverage packaging material. The use of these two types of plastic continuously, without good recycling, will have a negative impact on the environment. Building material waste is also becoming a serious environmental problem. This study aims to provide a solution to the problem of the above plastic waste and building material waste by making them into a mixture to be used as bricks. Research is carried out by mixing both materials, namely plastic heated at a temperature of $180-220^{\circ}C$ and building material waste that had been crushed and sized to 30-40 mesh with homogeneous stirring. The ratios of PET and LDPE plastic to building material waste are 9 : 1, 8 : 2, 7 : 3, 6 : 4 and 5 : 5. After heating and printing, density, water absorption and compressive strength tests are carried out. Addition of PET and LDPE plastic can increase compressive strength, and reduce water absorption, porosity and density. A maximum compressive strength of 10.5 MPa is obtained at the ratio of 6 : 4.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1617-1620
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• 1999

In this work, the effect of blend on physical and electrical properties investigated. The two kinds of low-density polyethylene (LDPE) whose densities are evaluated at $0.9179[g/cm^3]$ and $0.9192[g/cm^3]$, respectively, were used and blended according to the different blend ratio. The LDPE with the blend ratio of 50[wt%] represented the lowest impulse breakdown strength, $F_{BImp}$ at $30[^{\circ}C]$, but the highest $F_{BImp}$ at $90[^{\circ}C]$. DC breakdown strength, $F_{BDC}$. decreased with the increase of blend ratio at $30[^{\circ}C$, but increased at $60[^{\circ}C]$. The current density decreased with a blend ratio up to 75 [wt%] at $90[^{\circ}C]$. By analyzing the diffraction patterns of XRD, we found that the LDPE with the blend ratio of 50 [wt%] represented the largest crystal size of (020) plane. We investigated the relationship between the effect of blend and electrical properties and these results are discussed.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.504-510
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• 1996

Low-density polyethylene(LDPE)/Linear low-density polyethylene(LLDPE) blends were prepared by the compositional quenching process, a new morphology control method. The blends were characterized in terms of melting and crystallization behavior and mechanical properties. The results were compared with those of mechanically blended and solution blended samples. From DSC experiments, it was found that the melting temperatures and crystallization temperatures of the blends were dependent on the blending methods. In thermal property, LDPE/LLDPE blends prepared by compositional quenching process were similar to the blends prepared by solution blending but different from the blends prepared by mechanical blending. This result is explained to be due to the domain size dispersed in the matrix. The elongation-at-break and tensile strength of the samples blended by compositional quenching showed similar to those of the samples blended by solution blending method but larger than those of samples prepared by mechanical blending. Also, the Young's modulus showed the same trends as elongation-at-break. The tensile strength of the blends prepared by compositional quenching was not as high as the samples prepared by the other two blending methods.

• Food Science and Preservation
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• v.13 no.2
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• pp.168-173
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• 2006

To investigate the effect of grapefruit seed extract pretreatment and packaging materials on the quality of dried persimmon, dried persimmons were stored for $60{\sim}100$ days at room temperature $(15^{\circ}C)$ after dipping in grapefruit seed extract and then packing with LDPE (low density polyethylene) film and Nylon/LDPE film pouch $(30{\times}30cm^2)$. Weight loss of dried persimmon packaged with Nylon/LDPE film was not exceeded 86% of control. 60% mold occurrence and 50% browness were observed compared to control. There were no significant differences in the firmness, soluble solid content and color between grapefruit seed extract pretreatment and control. Grapefruit seed extracts pretreatment had an effect on the inhibition of color change in Hunters value.

• Food Science and Preservation
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• v.12 no.4
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• pp.305-309
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• 2005

To investigate the effects of cinnamon extracts pretreatment and packaging on the quality of dried persimmon. Dried persimmon were storaged during 100 days at room temperature($15^{\circ}C$) after dipping in cinnamon extracts and then packaging with LDPE(low density polyethylene) and Nylon/LDPE pouch Weight loss of dried persimmon treated with K-V was maintained $20.2\%$ lower than control. Firmness was $87\%$, browning was $56\%$ lower. Skin color change was 0.80 point, which was the lowest changes comparing with others. As a result, dipping in cinnamon extracts and packaging Nylon/LDPE film were good for maintaining dried qualities.