• Food Science and Biotechnology
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• v.14 no.5
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• pp.694-697
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• 2005

The objectives of this study were to compare the quality changes of cheese slices individually packed in four kinds of edible pouches in order to select the most suitable variety for individual packaging. The edible Z2 pouch (zein with oleic acid) was selected as maintaining the best cheese qualities based on the physical and microbiological changes undergone by the samples over 4-week storage at $5^{\circ}C$. The cheese sample individually packed in Z2 inner edible pouch and repacked in a plastic (OPP/LLDPE) outer pouch was not significantly different in physical and microbiological changes from that individually packed in a plastic (OPP/LLDPE) inner pouch and repacked in a plastic (OPP/LLDPE) outer pouch. Therefore, it may be concluded on the basis of the physical and microbiological evidence that the Z2 edible pouch can be used as an inner package for cheese slices when it is inside a plastic outer pouch.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05a
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• pp.37-40
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• 2000

LLDPE using power cable is used in electric insulators or dielectric materials because it is excellent in thermal properties or friendly environment but has defects of tree and accumulation of space charges. For the reason of that, it is blended with EVA to complement those problems. In this study, We made LLDPE/EVA samples that mixture ratio was 50:50, 60:40, 70:30, 80:20[W%] and studied physical and dielectric characteristics. We investigated the frequency and temperature dependency of tan 0 for mixtured samples in the temperature range of 25~110$[^{\circ}C]$, frequency range of $20{\sim}1\times10^6$ [Hz].

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.117-123
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• 2007

The effect of aluminium addition to MCM-41 on product yield and carbon number distribution was investigated in the catalytic cracking of a polymer mixture, LDPE, LLDPE, and EVA copolymer, with a composition similar to that found in real agricultural film wastes. Al-MCM-41 catalyst synthesized by post-synthetic grafting method (Al-MCM-41-P) as well as Al-MCM-41 catalyst synthesized by direct sol-gel (Al-MCM-41-D). The catalytic cracking of polymer mixture was carried out in vapor phase contact as well as in liquid phase contact. The amount of acid sites increased with aluminium addition by post method as well as direct method, which was seemed to be due to Lewis acid sites. In liquid phase catalytic cracking, the yield of light hydrocarbon fraction increased with aluminium addition. The effect of aluminium addition on production of $C_5-C_{12}$ hydrocarbons over Al-MCM-41-P catalysts was greater than that over Al-MCM-41-D catalysts. In the case of vapor phase catalytic cracking, the effect of aluminium addition was smaller than that of liquid phase catalytic cracking. The selectivity to $C_{13}-C_{32}$ hydrocarbons was smaller in vapor phase catalytic cracking.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.2
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• pp.41-48
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• 2018

A printable time temperature integrator (TTI) consisting of oxygen indicator and cover films with various oxygen permeability was developed. The printing ink contained methylene blue (oxygen indicator) which changed in color during storage. $TiO_2$ and glycerol for UV-activation of TTI and zein and ethanol for printing performance were also contained in the printing ink. The cover film on the ink was employed to control the color change rate and temperature dependency (Arrhenius activation energy, $E_a$) by using the different films (PE, PET, OPP, and LLDPE). The film properties were varied by annealing. TTI was produced by silk screen printing. As a result, the color change rates were different for the cover films, being the highest in TTI with LLDPE, followed by OPP, PE, and PET. The rate decreased with increase in the cover film thickness. The $E_a$ was the highest in TTI with LLDPE, followed by OPP, PE, and PET. The $E_a$ did not change with the cover film thickness. The annealed PVC and PET film were lower in oxygen permeability than the unannealed ones, indicating the lower color change rate.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.530-537
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• 2014

Moisture is a major factor causing the deteriorative physical change, microbial growth, and chemical reaction of the products. In this study, the moisture absorbing composite films have been prepared with moisture absorbing material of polyacrylic acid partial sodium salt (PAPSS) impregnated on LLDPE polymer for the functional packaging applications. The results showed that PAPSS impregnated film illustrated uniformly dispersed PAPSS particles in the LLDPE polymer matrix. The transparency of the PAPSS impregnated film decreased slightly at higher PAPSS concentrations. An increase in the PAPSS content for moisture-absorbing films showed a similar decrease in tensile strength, percent elongation at break, and tear strength. Their values of films impregnated with PAPSS of 0.5, 1, and 2% showed no significant difference. Meanwhile, 4% PAPSS films significantly decreased the values of mechanical properties compared to the films impregnated with different PAPSS levels. Values of the oxygen permeability and water vapor permeability for PAPSS impregnated films decreased significantly with greater PAPSS. The results indicate that 4% PAPSS impregnated in LLDPE films had high affinity of moisture absorbencies compared to the other films. The mathematical equation that best described the moisture sorption isotherm of each film sample was the GAB equation at $25^{\circ}C$. The crystallization and melting temperatures of PAPSS films were influenced by the addition of PAPSS material, but showed good thermal stability.

• Polymer(Korea)
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• v.33 no.5
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• pp.446-451
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• 2009

Reliability evaluations of linear low density polyethylene (LLDPE) pipe with respect of thermal exposure time have been investigated in accordance with RS M 0042, which is a reliability standard for polymer pipe. As the thermal exposure time is prolonged, a progressive increase, until 250 days, in tensile strength and a slight increase in hardness are observed, while a proportional decrease in elongation at break is showed. These results can be explained by the increase of crystallinity, followed by the increase of crosslinking density, chain scission and the decrease in chain mobility, due to thermal oxidation as the exposure time increases. Long term hydrostatic pressure test result implies the existence of transition point from ductile to brittle fracture. Oxidation induction time (OIT) test is employed to monitor the thermo-oxidative degradation of LLDPE pipe. This result shows that after the exposure time is 250 days, the depletion of antioxidants added in LLDPE pipe occurs. An empirical equation as function of exposure time, under $100^{\circ}C$ thermal-degradation condition, is proposed to assess the remaining amount of antioxidants owing to thermo-oxidative degradation. Fourier transform infrared spectroscopy results show the increase of carbonyl (-C=O) and hydroxyl (O-H) function groups on the surface of thermally exposed LLDPE pipe. This result suggests that the hydrocarbon groups locally undergo the oxidation on the LLDPE surface due to thermal-degradation.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.3
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• pp.163-171
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• 2017

Effects of different packaging methods for maintaining the shelf life and postharvest quality of iceberg lettuce (Lactuca sativa L.) were studied after harvesting in summer season. Lettuce heads were packaged in plastic crate with or without different films such as (A) Individual lettuce head sealed packaging with linear low density polyethylene (LLDPE) film; (B) Packaging lettuce head in plastic crate and wrapped with LLDPE film; (C): Individual lettuce head sealed packaging with perforated high density polyethylene (HDPE) film; (D) Packaging lettuce head in plastic crate and wrapped with perforated HDPE; and (E) Packaging lettuce head in plastic crate without any film (control), and stored at $2^{\circ}C$ for 35 days. Several quality parameters such as fresh weight loss, SPAD (soil & plant analyzer development) meter value, respiration rate, moisture content and appearance of lettuce were investigated. The lettuce wrapped with individually-sealed LLDPE film showed the lowest weight loss and the highest SPAD value rendering the best appearance index among the treataments throughout the three-week storage period at $2^{\circ}C$. Extending the freshness of iceberg lettuce during low temperature storage will definitely increase the salability potential in the domestic market even during summer season.

• 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.

• Proceedings of the Korean Fiber Society Conference
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• 1996.10a
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• pp.205-208
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• 1996

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1423-1430
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• 2012

The present study investigated the relationship between physical conditions and sensory properties of red pepper powder stored at different temperatures ($-20^{\circ}C$, $0^{\circ}C$, $20^{\circ}C$) and in different wrap materials (linear low density polyethylene, LLDPE; aluminum/linear low density polyethylene, Al/LLDPE). Red pepper powders with initial moisture contents of $17.35{\pm}0.32$% were not affected by the packaging material or storage temperature. Hunter a values of red pepper powder decreased while Hunter b values increased as storage temperature increased. There were no significant differences according to packaging materials. The American Spice Trade Association (ASTA) color value ($60.85{\pm}0.13$) significantly decreased with increasing temperature from $-20^{\circ}C$ to $20^{\circ}C$ ($21.70{\pm}0.06$ to $56.03{\pm}0.24$). The ASTA color value of samples packed with LLDPE ($21.70{\pm}0.06$) decreased more compared to samples packed with other materials. Further, capsanthin contents ($13.74{\pm}0.02$ mg/100 g) significantly decreased with increasing temperature from $-20^{\circ}C$ ($0.25{\pm}0.01$ to $0.28{\pm}0.01$ mg/100 g) to $20^{\circ}C$ ($0.13{\pm}0.01$ to $0.25{\pm}0.01$ mg/100 g). In the sensory evaluation of red pepper powder, overall acceptability was influenced by redness, yellowness, and pungency color. All physicochemical and sensory properties of red pepper powder were compared. Hunter a values, ASTA color values, and capsanthin contents were significantly associated with sensory preferences. In particular, ASTA color value showed a close relationship with color preference for red pepper (R2=0.922). Thus, we suggest that the preference for red pepper powder can be determined based on instrumental measurements of Hunter a values, ASTA color values, and capsanthin contents.