• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.272-277
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• 1998

In order to study storage stability of fresh jujube fruits (Zizyphus jujuba Miller) controlled atmosphere storage, polyethylene film packaging and non-packaging were compared. Jujube fruits were stored on the following gas compositions: 1.5% carbon dioxide and 5, 8, 10, 12% oxygen at $7^{\circ}C$, respectively. And 0.05 mm PE packaging and non-packaging were stored at $1^{\circ}C,\;4^{\circ}C\;and\;7^{\circ}C$. Safe storage period of Bokjo jujube fruits was four weeks when stored in CA condition of $O_2\;10%\;and\;CO_2\;1.5%$ in terms of their overall quality. The rate of weight loss was not much changed either by storage method of CA or by PE film packaging. In surface color the a value of jujube fruits increased but L and b values decreased during the storage period. Hardness showed the trend of increase in all the treatment for 2 weeks of storage while in CA it decreased more than the others after 4 weeks of storage. Soluble solids and titratable acidity were changed slightly. Vitamin C contents were gradually decreased in all treatments, but non-packed jujubes at $1^{\circ}C$ were slightly increased.

• Fashion & Textile Research Journal
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• v.23 no.2
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• pp.290-296
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• 2021

The effect of draw ratio (8, 10, 12, 14 times) and additive CaCO₃ content (0, 0.5, 1.0, 1.5, 2.0, and 3.0 wt%) on the properties of high-performance PE monofilament was investigated in this study. As the draw ratio increased (8-14 times), the melting enthalpy (ΔHf), crystallinity, specific gravity, and tensile strength increased significantly. However, the draw ratio had little effect on the melting temperature (Tm) and crystallization temperature (Tc). The seawater fastness (stain and fade) of the hydrophobic PE monofilament prepared in this study showed an excellent grade of 4-5 in all draw ratios. To investigate the effect of the additive CaCO₃ content on the properties of high-performance PE monofilament, the draw ratio was fixed at 14 times. It was found that the tensile strength of the PE monofilament sample containing 0.5 wt% of CaCO₃ was much greater compared to the sample without CaCO₃, but the elongation of the sample containing 0.5 wt% of CaCO₃ was much less than the sample with 0 wt% CaCO₃. However, in the case of the sample containing more than 0.5 wt% CaCO₃, the tensile strength slightly decreased and the elongation slightly increased as the CaCO₃ content increased. The seawater fastness (stain and fade) of the hydrophobic PE monofilament showed excellent grades of 4-5, regardless of the amount of additives. From the above results, it was found that the maximum draw ratio of 14 times with an additive of 0.5 wt% CaCO₃ are the optimal conditions for manufacturing high-performance marine fusion materials with various fineness (denier) with high strength and low elongation.

• Journal of Energy Engineering
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• v.14 no.2 s.42
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• pp.153-158
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• 2005

In order to investigate the short-term performance of polyethylene electrofusion joints, the mechanical tests and stress analysis have been conducted to the artificially defected weld joints. The defects of lack of fusion with a square-type were fabricated with 10, 20, 30, 40, 50, 60$\%$ size of the width of heat-ing wire zone, respectively. In this defect sires range, both tensile and bending test results showed the dependence of defect size to the electrofusion joints performance, but both sustained pressure and crush test results didn't. The numerical stress analysis results including the soil and internal pressures, tensile and bend-ing stresses clearly showed the dependence of fusion defect size. Based on both mechanical test and stress analysis results, the maximum acceptable defect size in polyethylene electrofusion joints is discussed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.147-151
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• 2003

Normal seed tubers and plug seedlings raised from stem cutting and mini-tubers ($10\pm3$ g) were planted or transplanted on August 20,2001 in bare soil or under transparent and black polyethylene film mulches to evaluate the effects of mulch material and seedling type on the growth and tuber yield of fall-grown potato (Solanum tuberosum L. cv. Dejima) in Jeju region. Total tuber number per plant was 4.6 regardless of mulch treatment, and direct planting seed potatoes resulted in the greatest tubers (5.14)/plant and followed by transplanting seedlings raised from cutting and mini-tubers (4.15 and 5.15 tubers/plant). Transparent and black polyethylene film mulches increased total tuber yield by 16 and 8%, respectively, and average tuber weight by 14 and 12%, respectively, compared with no mulch (21.16 t/ha and 72.2 g/tuber). Transplanting plug seedlings raised from cutting resulted in the greatest tuber yield, followed by transplanting plug seedlings raised from mini-tubers and direct planting seed potatoes.

• Polymer(Korea)
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• v.30 no.3
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• pp.224-229
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• 2006

Quaternary ammonium salt terminated silane was prepared from aminopropyldimethylethoxysilane with methyliodide and ionized 7,7,8,8-tetracyanoquinodimethane $(Li^+TCNQ^-)$ was prepared from TCNQ with methyliodide and lithium iodide. Quaternary ammonium salt silane-TCNQ adduct (ST) was prepared by reacting quaternary ammonium salt terminated silane with $Li^+TCNQ^-$ solution. Poly (dimethylsiloxane)-ST adduct (PST) was prepared by condensation of $\alpha,\omega-hydroxyl$ group terminated poly (dimethylsiloxane) (PDMS) with ST. Maleated polyethylene modified with PDMS (PST-g-MPE) was prepared by melt polymerization of maleated PE and PST in internal mixer and PST-g-MPE/carbon black (CB) and MPE/CB composites were prepared by compounding PST with MPE and PST-g-MPE, respectively. The thermal and mechanical properties of the composites were measured and dispersion characteristics of CB in matrix rosins show that the dispersion of CB in PST-g-MPE/CB was better than that of MPE/CB composite.

• Membrane Journal
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• v.24 no.6
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• pp.431-437
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• 2014

To overcome the flux reduction due to the fouling by adsorption of foulants onto the porous hydrophobic polyethylene membrane surface, the oxyflorination was introduced to hydrophilize the hydrophobic membranes. After the hydrophilization through oxyfluorination, the contact angle decreased from $93^{\circ}$ to $50^{\circ}$ while the water flux increased to 60%. It was considered that for the model foulants dissolved in water, such as albumin (form bovine serum, BSA), humic acid sodium salt (HA), and alginic acid sodium salt (SA), the flux was enhanced since the adsorbed foulants decreased by the oxyfluorination. Particularly, it was obtained that the water flux was over twice more than the untreated polyethylene membrane in case of SA foulant.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.446-453
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• 2021

Background: Plastic particles less than 5 mm in diameter (microplastics) are well-known for causing various toxicities such as lung inflammation, oxidative stress, genotoxicity, and reproductive toxicity. As microplastics become smaller, they can move across cell membranes, the placenta, and the blood-brain barrier. Objectives: We evaluated the toxicities of polyethylene microplastics (PE-PMs) in dams and neonates through intragastric intubation of pregnant ICR mice. Methods: Low concentrations (0.01 mg/mouse/day) and high concentrations (0.1 mg/mouse/day) of polyethylene microplastics were administered from the ninth day of pregnancy to postnatal day seven. The control group was administered with distilled water. On the day of sacrifice, the weight of dams and neonates and the organ weight of neonates was measured. Further, acetylcholinesterase levels and glutathione peroxidase levels were evaluated by using a blood sample obtained on the sacrifice day. Results: No significant difference in the number of neonates was found, but the body weight gain of dams was seen to be lower in the low-dose group. On the other hand, we observed a consecutively declining trend in the weight gain and organ weight of neonates among the high-, control, and low-dose groups. Meanwhile, the serum acetylcholinesterase and glutathione peroxidase level were higher in the low-dose group compared to the control group. Further, the dose-dependent accumulation of microplastics in the organs of neonates revealed the transport of plastic particles from dams to their offspring. Conclusions: Although the exact mechanism of toxicity caused by microplastics could not be confirmed, it was validated that exposure to microplastics during pregnancy and lactation causes its migration between generations and accumulation throughout the body. Hence, it is necessary to evaluate the systemic toxicity of microplastics and assessment of co-morbidities such as second-generation toxicity, neurotoxicity, and depression following long-term exposure.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.559-571
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• 2017

This study was conducted to determine the adhesive performances of plywoods affected by layering direction and the amounts of thermoplastic films. The face and back layers of veneer were hardwood species (Mixed light hardwood) and core layer veneer was radiata pine (Pinus radiata D. Don). Thermoplastic film used as adhesive were polypropylene (PP) film and polyethylene (PE) film. Thermal analysis and tensile strength were investigated on each films. As a result, the melting temperature of PP and PE films were $163.4^{\circ}C$ and $109.7^{\circ}C$, respectively, and the crystallization temperature were $98.9^{\circ}C$ and $93.6^{\circ}C$, respectively. Tensile strength and elongation of each films appeared higher on the width direction than length direction. Considering the characteristics of the thermoplastic films, the test for the amount of film used was carried out by layering film to the target thickness on veneer. The effecting of layering direction of film on plywood manufacturing was conducted by laminating in the length and width directions of the film according to the grain direction of veneer. Tensile-shear strength of plywood in wet condition was satisfied with the quality standard (0.7 MPa) of KS F 3101 when the film was used over 0.05 mm of PP film and over 0.10 mm of PE film. Tensile-shear strength of plywood after cyclic boiling exceeded the KS standard when PP film was used 0.20 mm thickness. Furthermore, higher bonding strength was observed on a plywood made with width direction of film according to grain direction of veneer than that of length direction of film. Based on microscopic analysis of the surface and bonding line of plywood, interlocking between veneers by penetration of a thermoplastic film into inner and cracks were observed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.2
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• pp.192-198
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• 2006

Treatment effects of grape fruit stem extracts (GFSE) containing trans-resveratrol on the storage property of fresh jujube (Zizyphus jujube) were investigated. Fresh jujubes were packed in different storage containers [polyethylene terephthalate (PET) and polyethylene (PE)], and treated with GFSE containing trans-resveratrol of 10, 30 and 50 ppm, respectively. The storage vessels filled with $N_2$ gas, and stored in refrigerator $(0{\pm}1^{\circ}C)$ during 18 weeks, and then quality characteristics during storage period were analysed. Ethylene gas increased until 8 weeks and decreased afterward. Decaying of jujube started at $6\~8$ weeks in control, but it did at 14 week storage for the fruits at $50\%$ maturity treated with 10 ppm of GFSE and packed in PE vessel. Soluble solid (Brix degree) and total acidity of fresh jujube slightly increased in all the treatments during storage period. Hardness slightly increased until 4 weeks and decreased afterward. Vitamin C content was at the highest content of $86.8\~273.4$ mg/100g for most of treatments at 2 weeks and decreased afterward. Storage stability was higher for $50\%$ maturity fruits than for the $70\%$ maturity, and higher for PE vessels than PET containers. Storage period of fresh jujube in this experiment ranges in $10\~12$ weeks for $50\%$ maturity fruits treated with 10 ppm of GFSE and packed in PE vessel.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.3
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• pp.153-161
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• 2023

The worldwide effects of COVID-19 have led to a surge in online shopping and contactless services. The consumption pattern has caused the issues such as the environmental pollution together with the increase of plastic waste. Reducing the reliance on the petroleum based plastic use for the package and replacing it with environmentally friendly material are the simple ways in order to solve those problems. Paper is an eco-friendly product with high recyclability as the food packaging materials but has still poor barrier properties. A barrier coating on surface of the paper can be achieved with the proper packaging materials featuring water, gas and grease barrier. Polyethylene (PE) or polypropylene (PP) coatings which are generally laminated or coated to paper are widely used in food packaging applications to protect products from moisture and provide water or grease resistance. However, recycling of packaging containing PE or PP matrix is limited and costly because those films are difficult to degrade in the environment. This study investigated the recyclability of modified acrylic emulsion coating papers compared to PE and PP polymer matrixes as well as their mechanical and gas barrier properties. The results showed that PE or modified acrylic emulsion coated papers had better mechanical properties compared to the uncoated paper as a control. PE or PP coating papers showed strong oil resistance property, achieving a kit rating of 12. Those papers also had a significantly higher percentage of screen reject during the recycling process than modified acrylic coated paper which had a screen rejection rate of 6.25%. In addition an uncoated paper had similar value of a screen rejection rate. It may suggest that modified acrylic emulsion coating paper can be more easily recycled than PE or PP coating papers. The overall results of the study found that modified acrylic emulsion coating paper would be a viable alternative to suggest a possible solution to an environmental problem as well as enhancing the weak mechanical and poor gas barrier properties of the paper against moisture.