• Polymer(Korea)
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• v.30 no.2
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• pp.168-174
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• 2006

To utilize as highly functional scaffolds for tissue engineering by improving hydrophobicity and cell compatibility of the exist polymer scaffolds, the biodegradable poly(L-lactic acid) (PLLA) films and scaffolds having the optimal hydrophilicity were prepared by in situ plasma treatment and grafting of a carboxyl acid-containing monomer, acrylic acid (AA) in the chamber. From the results of surface analyses, surface-modified nonporous PLLA film and dual pore scaffold surfaces showed high hydrophilicity due to the decrease in contact angle and the increase in carboxylic groups as compared with untreated PLLA control. In particular, among various surface modification methods, Ar(argon)+AA+AA sample prepared by Ar plasma and then acrylic acid treatments displayed lower contact angle and more carboxylic groups thar Ar/AA and Ar+TP(thermal polymerization) samples, indicating that Ar+AA+AA sample was optimally treated for improving its hydrophilicity. In the cases of surface modified nonporous PLLA films and dual pore scaffolds, the adhesion and proliferation of chondrocytes increased with increasing their hydrophilicity.

• Clean Technology
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• v.27 no.2
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• pp.124-131
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• 2021

As declarations of carbon neutrality are spreading throughout the world, much research is being conducted on biodegradable polymers. In this study, nanocellulose, which comprises the largest amount of natural polymer currently available in the world, was proposed as a substitute for non-biodegradable polymers. We chose to modify the surface functional group of crystalline nanocellulose using glycidoxypropyl trimethoxysilane (GPTMS), which is a silane coupling agent, and the product was then used to form a film with low density polyethylene (LDPE). We then conducted measurements using a Fourier transform infrared spectrophotometer (FT-IR) in addition to measuring hydrophilic/lipophilicity of the surface functional group modification of crystalline nitrocellulose as well as that of a polymer composite using the hybrid nanocellulose (H-NC). For compatibility with petroleum-based polymers, the best tensile strength and transparency was found when the H-NC was reacted at pH 14 and 1 wt% compared with LDPE. From the test results, we found that it is possible to modify the surface functional groups of nanocellulose using a silane coupling agent. In addition, the high compatibility of nanocellulose with petroleum-based polymers is expected to help in reaching carbon neutrality by reducing the use of fossil fuels.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.30 no.1
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• pp.63-72
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• 2024

Poly (butylene adipate-co-terephthalate) (PBAT) is one of the representative biodegradable polymers with high ductility and processability to replace petroleum-based polymers. Many investigations have been conducted to broaden the applications of PBAT in a variety of industries, including the food packaging, agricultural mulching film, and logistics and distribution fields. Foaming process is widely known technique to generate the cell structure within the polymer matrix, offering the insulation and light weight properties. However, there was no commercially feasible foam product based on biodegradable polymers, especially PBAT, and maintaining a proper melt viscosity of the polymer would be a key parameter for the foaming process. In this study, chemical foaming agent and cross-linking agent were introduced to PBAT, and a compression molding process was applied to prepare a foam sheet. The correlation between cell morphological structures and mechanical and physical properties was evaluated. It was found that PBAT with foam structures effectively reduced the density and thermal conductivity, allowing them to be suitable for applications such as insulation and lightweight packaging or cushion materials.

• Journal of Life Science
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• v.34 no.8
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• pp.540-547
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• 2024

The continuous use of polymer materials has exacerbated waste and environmental challenges, spurring a growing interest in eco-friendly polymers, especially biodegradable polymers. These polymers are gaining attention for their potential as antimicrobial agents, particularly in fields like food packaging a need further underscored by the recent COVID-19 pandemic. This study focuses on the development of an antibacterial polymer by combining poly-butylene adipate terephthalate (PBAT) with zinc pyrithione (ZnPt). The antibacterial properties were assessed through turbidity analysis, the shaking flask method, and the film adhesion method. The antibacterial activities of the composites with varying ZnPt% (w/w) contents (0, 0.1, 0.3, and 0.5) were evaluated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Results revealed that even at a low concentration of 0.1% (w/w), the composites demonstrated significant antibacterial activity against both Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli). Composites with ZnPt concentrations of 0.3% (w/w) or higher achieved over 99.999% antibacterial efficacy. Field emission scanning electron microscopy (FE-SEM) analysis of the fracture surfaces of the composites confirmed the uniform distribution of ZnPt particles, ranging from 1-4 ㎛. Further FE-SEM analysis of bacterial suspensions exposed to the composite surfaces showed clear evidence of cell wall destruction in both E. coli and S. aureus. As an antimicrobial biodegradable polymer, PBAT-ZnPt composites show great promise for applications in various sectors, including food packaging.

• 한국유가공학회:학술대회논문집
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• 2002.04a
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• pp.59-60
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• 2002

Edible films such as wax coatings, sugar and chocolate covers, and sausage casings, have been used in food applications for years$^{(1)}$ However, interest in edible films and biodegradable polymers has been renewed due to concerns about the environment, a need to reduce the quantity of disposable packaging, and demand by the consumer for higher quality food products. Edible films can function as secondary packaging materials to enhance food quality and reduce the amount of traditional packaging needed. For example, edible films can serve to enhance food quality by acting as moisture and gas barriers, thus, providing protection to a food product after the primary packaging is opened. Edible films are not meant to replace synthetic packaging materials; instead, they provide the potential as food packagings where traditional synthetic or biodegradable plastics cannot function. For instance, edible films can be used as convenient soluble pouches containing single-servings for products such as instant noodles and soup/seasoning combination. In the food industry, they can be used as ingredient delivery systems for delivering pre-measured ingredients during processing. Edible films also can provide the food processors with a variety of new opportunities for product development and processing. Depends on materials of edible films, they also can be sources of nutritional supplements. Especially, whey proteins have excellent amino acid balance while some edible films resources lack adequate amount of certain amino acids, for example, soy protein is low in methionine and wheat flour is low in lysine$^{(2)}$. Whey proteins have a surplus of the essential amino acid lysine, threonine, methionine and isoleucine. Thus, the idea of using whey protein-based films to individually pack cereal products, which often deficient in these amino acids, become very attractive$^{(3)}$. Whey is a by-product of cheese manufacturing and much of annual production is not utilized$^{(4)}$. Development of edible films from whey protein is one of the ways to recover whey from dairy industry waste. Whey proteins as raw materials of film production can be obtained at inexpensive cost. I hypothesize that it is possible to make whey protein-based edible films with improved moisture barrier properties without significantly altering other properties by producing whey protein/lipid emulsion films and these films will be suitable far food applications. The fellowing are the specific otjectives of this research: 1. Develop whey protein/lipid emulsion edible films and determine their microstructures, barrier (moisture and oxygen) and mechanical (tensile strength and elongation) properties. 2. Study the nature of interactions involved in the formation and stability of the films. 3. Investigate thermal properties, heat sealability, and sealing properties of the films. 4. Demonstrate suitability of their application in foods as packaging materials. Methodologies were developed to produce edible films from whey protein isolate (WPI) and concentrate (WPC), and film-forming procedure was optimized. Lipids, butter fat (BF) and candelilla wax (CW), were added into film-forming solutions to produce whey protein/lipid emulsion edible films. Significant reduction in water vapor and oxygen permeabilities of the films could be achieved upon addition of BF and CW. Mechanical properties were also influenced by the lipid type. Microstructures of the films accounted for the differences in their barrier and mechanical properties. Studies with bond-dissociating agents indicated that disulfide and hydrogen bonds, cooperatively, were the primary forces involved in the formation and stability of whey protein/lipid emulsion films. Contribution of hydrophobic interactions was secondary. Thermal properties of the films were studied using differential scanning calorimetry, and the results were used to optimize heat-sealing conditions for the films. Electron spectroscopy for chemical analysis (ESCA) was used to study the nature of the interfacial interaction of sealed films. All films were heat sealable and showed good seal strengths while the plasticizer type influenced optimum heat-sealing temperatures of the films, 130$^{\circ}$C for sorbitol-plasticized WPI films and 110$^{\circ}$C for glycerol-plasticized WPI films. ESCA spectra showed that the main interactions responsible for the heat-sealed joint of whey protein-based edible films were hydrogen bonds and covalent bonds involving C-0-H and N-C components. Finally, solubility in water, moisture contents, moisture sorption isotherms and sensory attributes (using a trained sensory panel) of the films were determined. Solubility was influenced primarily by the plasticizer in the films, and the higher the plasticizer content, the greater was the solubility of the films in water. Moisture contents of the films showed a strong relationship with moisture sorption isotherm properties of the films. Lower moisture content of the films resulted in lower equilibrium moisture contents at all aw levels. Sensory evaluation of the films revealed that no distinctive odor existed in WPI films. All films tested showed slight sweetness and adhesiveness. Films with lipids were scored as being opaque while films without lipids were scored to be clear. Whey protein/lipid emulsion edible films may be suitable for packaging of powder mix and should be suitable for packaging of non-hygroscopic foods$^{(5,6,7,8,)}$.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.379-384
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• 1998

Biodegradable carrageenan films and carrageenan-coated papers were developed and their characteristics of lipid permeation was investigated for possible substitution of PE-coated papers used in packaging of oily or greasy foods. Both carrageenan coated papers and free carrageenan films were highly resistant to lipid penetration. Among the carrageenans tested, ${\kappa}-carrageenan$ film showed the most resistant followed by ${\lambda}-$ and i-carrageenan films. The resistance to lipid increased as the thickness of ${\kappa}-carrageenan$ layer increased. Carrageenan coated papers with $4\;and\;5\;kg/ream\;(278m^2)$ showed the lipid resistance comparable to that of the PE-coated paper. Free films also showed the same trends of the lipid resistance as the carrageenan coated papers, but the degree of lipid resistance was approximately ten times higher than that of carrageenan coated paper. Degree of lipid penetration of carrageenan films and carrageenan-coated papers increased exponentially against time. ${\kappa}-carrageenan$ coated papers over 4 kg/ream showed to have an adequate lipid barrier property for being utilized for packaging greasy food products.

• Polymer(Korea)
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• v.35 no.1
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• pp.7-12
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• 2011

Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable synthetic polymer with acceptable mechanical strength and well-controlled degradation rate. Also, it can be easily fabricated into many shapes. Silk fibroin contains powerful bioactive molecules. We fabricated natural/synthetic hybrid films using 0, 10, 20, 40 and 80 wt% of silk fibroin. Schwann cells (SCs) were seeded on PLGA/silk fibroin hybrid films and confirmed the effects of adhesion and proliferation on SCs according to the content of silk fibroin. In this study, we confirmed PLGA/silk fibroin hybrid film containing 40% and 80% of silk fibroin interrupted adhesion and proliferation of SCs. Films containing 10% and 20% of silk, however, provided suitable environment for growth and proliferation of SCs. These results suggest that silk fibroin provides suitables surface to neural cells and its proper content provides proper culture conditions to improve cell adhesion and proliferation.

• KSBB Journal
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• v.16 no.3
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• pp.302-306
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• 2001

The possibility of biomaterials prepared from natural polymer as a skin substitute was evaluated by measuring biocompatibility. Biodegradable films were prepared by solution blend method in the weight ratio of chitosan for the purpose of useful biomaterials. These films were inserted in the back of rat and their biodegradability was investigated by the film weight and hematology as a function of time for the biotransformation. The result of rat test showed that medium, high viscosity chitosan induced some suspects of inbiocompatibililty in the tissue by foreign body reaction 48 and 72 hours after implantation. Also, we prepared the official burn ointment which is made by low viscosity chitosan. This burn ointment was covered on the skin wound of artificial burn and their effect of healing was investigated by the evaluation of the naked eye and hematological change as a function of time. The result of rats test showed that burn ointments made from chitosan was effective reduction of inflammation than negative group.

• Polymer(Korea)
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• v.36 no.3
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• pp.309-314
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• 2012

To control degradation rate of biodegradable poly(lactide)s (PLA), the stereochemical PLAs with different ratios of $d$-lactide and $l$-lactide units were synthesized by the ring open polymerization and a degradation behavior was measured by a Langmuir film balance. Degradation rates of mixture monolayers on alkaline subphase were investigated as a function of optical purity of mixture component, 100, 99, 97 and 95%. As increasing their optical purity, melting temperatures of mixtures from stereocomplexation increased. The degradation rate of mixture monolayer with 100% optical purity was much slower than that of each homopolymer one and the others showed 2 step degradation behaviors. In the first step, the degradation which is faster than that of each homopolymer occurs in the uncomplexed region, and secondly, the degradation occurred in the complexed region which showed similar degradation rate to that of 100% optical purity. These results indicate that the alkaline degradation of stereochemical PLAs could be controlled by stereochemistry and stereocomplexation between enantiomer PLAs.

• Macromolecular Research
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• v.14 no.5
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• pp.552-558
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• 2006

Biodegradable nanofibrous poly(L-lactic acid) (PLLA) scaffold was prepared by an electrospinning process for use in tissue regeneration. The nanofiber scaffold was treated with oxygen plasma and then simultaneously in situ grafted with hydrophilic acrylic acid (AA) to obtain PLLA-g-PAA. The fiber diameter, pore size, and porosity of the electrospun nanofibrous PLLA scaffold were estimated as $250\sim750nm,\;\sim30{\mu}m$, and 95%, respectively. The ultimate tensile strength was 1.7 MPa and the percent elongation at break was 120%. Although the physical and mechanical properties of the PLLA-g-PAA scaffold were comparable to those of the PLLA control, a significantly lower contact angle and significantly higher ratio of oxygen to carbon were notable on the PLLA-g-PAA surface. After the fibroblasts were cultured for up to 6 days, cell adhesion and proliferation were much improved on the nanofibrous PLLA-g-PAA scaffold than on either PLLA film or unmodified nanofibrous PLLA scaffold. The present work demonstrated that the applications of plasma treatment and hydrophilic AA grafting were effective to modify the surface of electrospun nanofibrous polymer scaffolds and that the altered surface characteristics significantly improved cell adhesion and proliferation.