• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.2
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• pp.67-74
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• 2017

In this work, the effects of nano $TiO_2$ on functionality and stability of low density polyethylene (LDPE) composite films were investigated for food packaging application. LDPE-nano $TiO_2$ composite films were prepared with various $TiO_2$ contents (0, 0.5, 1.0, 3.0 and 5.0wt%) by melt-extrusion and their basic properties such as crystallinity, chemical bonds and surface morphology were examined by XRD, FTIR and SEM. Ultraviolet (UV) light barrier property of as-prepared LDPE-nano $TiO_2$ composite films was also studied and the presence of nano $TiO_2$ resulted in significant improvement of UV light barrier compared to the pure LDPE film. To evaluate influence of nano $TiO_2$ on LDPE properties required as packaging material, thermal, mechanical, gas barrier and optical properties of LDPE-nano $TiO_2$ composite films were characterized with various analytical techniques including TGA, UTM, OTR, WVTR and UV-vis spectroscopy. As a result, except optical property of LDPE, no significant effects were found in other properties. Opacity of pure LDPE was greatly increased with increasing concentration of nano $TiO_2$.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.1
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• pp.27-34
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• 2018

In this work, nano ZnO was introduced into low density poly ethylene (LDPE) composites films with various contents (0, 0.5, 1.0, 3.0 and 5.0 wt%) by melt-extrusion. Their basic properties such as crystallinity, chemical bonds and surface morphology were examined by XRD, FTIR and SEM. XRD patterns and FTIR peaks intensity were increased in proportion to the ZnO contents. SEM images showed well dispersed nano ZnO in LDPE composite films. Antimicrobial functionality of LDPE-nano ZnO composite films was also studied and the presence of nano ZnO resulted in significant improvement of antimicrobial functionality compared to the pure LDPE film. To evaluate influence of nano ZnO on LDPE properties required as packaging material, thermal, mechanical, gas barrier and optical properties of LDPE-nano ZnO composite films were characterized with various analytical techniques including TGA, UTM, OTR, WVTR and UV-Vis spectroscopy. As a result, except optical and mechanical properties of LDPE, no significant effects were found in other properties. Opacity of pure LDPE was greatly increased with increasing concentration of nano ZnO and tensile strength was also improved at 0.5wt% ZnO content.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.22 no.3
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• pp.85-93
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• 2016

Flower-like zinc oxide (FZnO) was successfully synthesized via a sonochemical process. The chemical structure, morphology, and antimicrobial properties of as- prepared FZnO were investigated. Additionally, pure LDPE and five different LDPE/FZnO composite films were prepared with different FZnO content by using a twin screw extruder. According to the FTIR and SEM analyses, there exists weak interfacial interaction between LDPE and FZnO. Compared with pure LDPE, the LDPE/FZnO composite films showed UV barrier and enhanced antimicrobial activity against Escherichia coli (E. coli) as a Gram-negative micro-organism and Staphylococcus aureus (S. aureus) as a Gram-positive micro-organism. To enhance the interfacial interaction and good dispersion of FZnO into the LDPE matrix, and resultantly to such as UV barrier and antimicrobial properties of LDPE/FZnO composite films as the packaging materials, further efforts are required.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.3
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• pp.149-157
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• 2018

Low density polyethylene (LDPE) has been researched in many industrial applications, and LDPE/zeolite 4A composites has been extensively studied for many applications such as microporous, breathable film and so on. LDPE/zeolite composite have a great potential for carbon dioxide adsorption film due to its high adsorption ability. In this study, LDPE/zeolite 4A composites with various contents were prepared by melt mixing process, and co-extrusion process was applied to develop a $CO_2$ adsorption conventional film and foamed film. The thermal, rheological, mechanical, physical and morphological properties of composite films has been characterized, and $CO_2$ adsorption of the composite films evaluated by thermogravimetric analysis (TGA) and the performance was found to be about 18 cc/g at 30.9 wt% of the zeolite content.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.1
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• pp.41-48
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• 2021

In this study, ethylene vinyl acetate (EVA) and low density polyethylene (LDPE) composite films (EVA/LDPE-OSP) containing calcined oyster shell powder (OSP) were prepared using twin-screw extruder as an antimicrobial packaging material. The OSP composite was initially prepared and then incorporated into an EVA/LDPE blend at different ratios (0, 1, 3 and 5%) to develop the EVA/LDPE-OSP composite films. The as-prepared EVA/LDPE-OSP composites films were evaluated using FT-IR, DSC, TGA, OTR, WVTR, SEM and UTM as well as antimicrobial activity was examined using JIS Z 2801:2000 standard. OPS endowed the antimicrobial potency to the composite films against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. In addition, the incorporation of OSP remarkably enhanced the thermal stability. OSP as a natural biocidal agent can be used as a multifunctional additive in packaging industry such as improving the thermomechanical properties and preventing the microbial contamination of packaged products.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.23-28
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• 2015

Lacquer sap extracted from lacquer trees exhibits good thermal stabilities and antimicrobial properties. To apply these superior properties to functional packaging, polyurushiol (YPUOH) powders were prepared and blended into LDPE (low density polyethylene) to prepare three different LDPE/YPUOH composite films via a twin screw extruder system. Their morphology, thermal and antimicrobial properties as well as barrier properties of the LDPE/YPUOH composite films were thoroughly investigated to find out applicablities of the films as functional packaging materials. Although the interfacial interaction between LDPE and YPUOH was relatively weak, LDPE/YPUOH composite films exhibited good dispersion of YPUOH in LDPE, resulting in the enhanced thermal stability with YPUOH loading. Due to the good antibacterial property of as-prepared YPUOH, LDPE/YUOH composite films also showed an excellent antibacterial activity (R) of 99.9% against E. coli. Furthermore, the moisture barrier property of LDPE/YPUOH composite films increased with increasing YPUOH contents. Incorporating the relatively low amount of YPUOH in LDPE resulted in the apparent enhancement in thermal stabilities, antibacterial and moisture barrier properties, which made them promising candidates as a functional filler for packaging materials.

• Korean Journal of Food Science and Technology
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• v.26 no.3
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• pp.283-287
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• 1994

The effects of packaging methods on the storage properities of salted Chinese cabbage were examinined during 3-week storage. The weights of salted Chinese cabbage decreased to 69-77% by water loss and salinities decreased from 2.6% to 2.0%, respectively. The pH decreased from 6.4 to 6.2 for 1- week storage in all cases, but the pH increased to 6.6 in non packaging(Non-P), maintained at 6.2 in PVC container packaging(PVC), and decreased continuously to 5.5 and 5.7 in LDPE packaging (LDPE) and HDPE packaging(HDPE), repectively for 3-week storage. Reducing sugars increased slightly for 1-week storage for the relative concentration effect by water loss, but decreased to 1.8% for 3-week storage because of the microbial fermentation. Cutting force increased in LDPE for the continuous osmosis phenomena but decreased in Non-P for the putrefaction. As the results, LDPE was found to be the most effective packaging method.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.546-553
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• 2012

Urushiol extracted from lacquer tree exhibits good thermal stabilities as well as antimicrobial andantioxidant properties. However, it has been known that the urushiol derivates bring out allergy. In this study, polyurushiol (PUOH) powders were successfully synthesized for the safe and convenient handling of allergic urushiol. First, the as-synthesized PUOH was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermal gravimetric analyzer (TGA), antioxidant test and antimicrobial test. And then, six different LDPE/PUOH composite films were prepared via a twin screw extruder system and investigated their feasibility to use as active packaging materials. Their chemical structures, morphology, thermal optical and antimicrobial properties of the LDPE/PUOH composite films were investigated as a function of PUOH contents. FTIR and SEM results showed that LDPE/PUOH composite films have a weak interfacial interaction and poor dispersion with a high PUOH loading. The thermal properties increased up to 3 wt% as the content of PUOH increases. Compared to the pure LDPE films, LDPE/PUOH composite films are more effective in the UV absorbance and antibacterial activity against E. coli. To maximize the performance of LDPE/PUOH compositefilms as the packaging materials, further researches are required to enhance the dispersion of PUOH powders in the LDPE matrix.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.21 no.3
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• pp.107-113
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• 2015

This work focused on the study of thermal properties and kinetic behavior of LDPE-nanoclay composite films. The effect of nanoclay content (0.5, 1, 3, and 5 wt%) on thermal stability and crystallization characteristics of the nanocomposites were investigated by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results from endothermic curve showed that the nanoclay played an important role in the crystallization of nanocomposites by acting as nucleating agent. From exothermic curve, there was a crystallization temperature shift which was attributed to crystallization process induced by nanoclay. The TGA results showed that the addition of nanoclay significantly increased the thermal stability of LDPE matrix, which was likely due to the characteristic of layered silicates/clays dispersed in LDPE matrix as well as the formation of multilayered carbonaceous-silicate char. A well-known Coats-Redfern method was used to evaluate the decomposition activation energy of nanocomposite. It was demonstrated that introducing of nanoclay to LDPE matrix escalated the activation energy of nanocomposite decomposition resulting in thermal stability improvement.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.3
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• pp.125-132
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• 2017

The effect of food simulants on properties and light barrier function of LDPE-nano $TiO_2$ composite film has been investigated. LDPE-nano $TiO_2$ composite films were prepared with 5.0wt% $TiO_2$ content by melt-extrusion. To simulate food contact environment, according to KFDA standards and specifications for food utensils, containers and packages, food simulants were selected with deionized water, 50% ethanol, 4% acetic acid and n-heptane and composite films were immersed in each food simulant at $70^{\circ}C$, 30 min except n-heptane ($25^{\circ}C$, 60 min). A variety of material properties, including crystallinity, chemical bonds, surface morphology, mechanical, oxygen barrier and optical properties, of LDPE-nano $TiO_2$ composite film were examined with and without the food simulants treatment. As a result, under regulated migration condition, LDPE-nano $TiO_2$ composite showed extremely stable in all properties tested in the study in contact with food simulants indicating that $TiO_2$ nanoparticles are physicochemically stable and quite compatible with LDPE. Results enable us to anticipate migration of $TiO_2$ will probably not occur. To evaluate influence of migration of $TiO_2$ on food stuffs, their color, pH and acidity were observed as well.