• Polymer(Korea)
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• v.38 no.1
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• pp.93-97
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• 2014

Biodegradable drug-eluting stent has dual functions of supporting the lumen and treating internal tumor preventing the restenosis by releasing drug. In this study, the polycaprolactone (PCL) based three dimensional (3D) mesh loaded with paclitaxel (PTX) was presented by rapid prototyping (RP) technique of solid freeform fabrication (SFF) for biodegradable drug-eluting stent application. PCL has many advantageous properties such as good biocompatibility, good mechanical properties, and good drug permeability. PTX is widely used in the cancer treatment by inhibiting tumor cell proliferation. Analytical methods of HPLC and NMR were used for simultaneous quantification of PTX. Scanning electron microscopy (SEM) was performed to observe the architecture and morphologies of 3D mesh. The cytotoxicity assay results indicated released PTX's biological activity. This study provided that PCL based 3D mesh loaded with PTX by RP technique has great potential for biodegradable drug-eluting stent application.

• Clean Technology
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• v.17 no.3
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• pp.191-200
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• 2011

Natural polymers, biopolymers, and synthetic polymers based on renewable resources are the basis for the 21th portfolio of sustainable and eco-friendly plastics but high-volume consumable plastics continue to be dominated by nondegradable petroleum-based materials. Three factors have recently made biodegradable polymers economically attractive: (i) rising costs of petroleum production resulting from the depletion of the most easily accessible reserves, (ii) environmental and economic concerns associated with waste plastics, and (iii) emissions of carbon dioxide from preparation of petroleum-based materials. These pressures have driven commercial applications based on biodegradable polymers which are related to reduction of carbon dioxide in processing, such poly(hydroxy alkanoate) and poly (lactide). Since initial degradation of these polymers leads to catastrophic mechanical failure, it is necessary to control the rate of initial degradation for commercial applications. In this article, we have a critic review on the recent progress of polymer modification for the control of degradation.

• Composites Research
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• v.35 no.6
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• pp.419-424
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• 2022

Using non-biodegradable polymers is a severe environmental problem as they are not recyclable and generate a large amount of waste. Biopolymers, such as starch-based composites, have been considered one of the most promising replacement materials. These eco-friendly materials have the advantage of being low-cost, biodegradable, and obtained from renewable sources. However, as starch tends to be brittle and hydrophilic, it can make these materials unusable when exposed to water and limit its processability for further applications. In this work, a biobased modified starch was grafted using two bioderived materials, lauryl methacrylate (LMA) and tetrahydrofurfuryl methacrylate (THFMA), by radical polymerization. A polylactic acid (PLA) composite based on the modified starch (m-St) was fabricated to enhance its toughness. These samples were characterized by Fourier transform infrared, ¹H NMR and ¹³C NMR analysis, optical and scanning electron microscopy. The starch was successfully grafted, thus improving the compatibility with the PLA matrix. The mechanical properties of these films were also studied. Results from mechanical tests showed a slight enhancement of the mechanical performance of these composites when m-St was added to the PLA matrix. Such behavior is related to the improved dispersion of m-St 1:2 on PLA, confirmed by SEM images showing enhanced compatibility between modified starch and PLA matrix. This indicated excellent properties of the produced composite film for further eco-friendly applications.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.35-45
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• 2017

In order to improve the anaerobic digestion efficiency of the sewage sludge, the methane potential of the hydrolysate generated from the hydro-thermal reaction at 170, 180, 190, 200, 210, $220^{\circ}C$ was analyzed and the constitutional characteristics of the organic materials were estimated by dividing organic materials of hydro-thermal hydrolysate into easily biodegradable, decomposition resistant, and non-biodegradable organic materials applying the parallel first order kinetics model. The ultimate methane potential of sewage sludge hydro-thermal hydrolysate increased to 0.39, 0.39, 0.40, 0.44, 0.45, and $0.46Nm^3/kg-VS_{added}$ as hydro-thermal reaction temperature increased from 170, 180, 190, 200, 210, $220^{\circ}C$. It has been shown that the organic matter of sewage sludge is solubilized to increase the content of biodegradable organic material($VS_B$). The easily degradable organic matter($VS_e$) content was highest at hydro-thermal reaction temperature of 200 and $210^{\circ}C$, and optimum hydro-thermal reaction temperature for organic matter solubilization of sewage sludge was in the range of $200{\sim}210^{\circ}C$. In addition, the amount of biodegradable organic material($VS_B$) and easily biodegradable organic matter ($VS_e$) in the hydrolysate of sewage sludge was the highest at hydro-thermal reaction temperature of $200^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.1
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• pp.73-78
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• 2017

This study was conducted to elucidate the effects of mulching materials on root growth characteristics and weed occurrence of Platycodon grandiflorum transplants (3 years old) in organic farming. After transplanting, roots were mulched with one of three mulching materials (biodegradable film, sawdust, or rice husks) or a control (no mulching). The average root diameter of all mulching groups was 28.1 mm, which was 5.1 mm thicker than the no-mulching treatment. Roots with the biodegradable film treatment were the thickest at 30.9 mm. Root length was the shortest, 22.0 cm, with rice husk mulching. The number of rootlets was the highest with film mulching (36.0 rootlets/root) and the lowest with no mulching. For root fresh weight, which directly affects yield, the average of treated and untreated roots was 100 and 56 g/root, respectively. The highest fresh weight was in the biodegradable film plot (130 g/root). The mulching treatment groups showed a weed inhibition effect compared with the no-mulching treatment. The dominant weeds with the no-mulching treatment were Setaria viridis and Digitaria ciliaris, and that with the mulching treatment was Setaria viridis. Average annual weed occurrence across all treatments was 72%. Weed occurrence was the highest with the no-mulching treatment ($125weeds/m^2$), and there were no weeds with the biodegradable film treatment.

• Advanced Composite Materials
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• v.16 no.4
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• pp.385-394
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• 2007

In this study, the effect of molding condition on the tensile properties for plain woven hemp fiber reinforced green composite was examined. The tensile properties of the composite were compared with those of the plain woven jute fiber composite fabricated by the same process. Emulsion type biodegradable resin or polypropylene sheet was used as matrix. The composites were processed by the compression molding where the molding temperature and its heating time were changed from 160 to $190^{\circ}C$ and from 15 to 25 min, respectively. The following results were obtained from the experiment. The tensile property of hemp fiber reinforced polypropylene is improved in comparison with polypropylene bulk. The strength of composite is about 2.6 times that of the resin bulk specimen. Hemp fiber is more effective than jute fiber as reinforcement for green composite from the viewpoint of strength. The molding temperature and time are suitable below $180^{\circ}C$ and 20 min for hemp fiber reinforced green composite. Hemp fiber green composite has a tendency to decrease its tensile strength when fiber content is over 50 wt%.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.341-344
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• 2001

Over the last 20 years, biodegradable materials in medical applications have been studied extensively. Among these materials, poly(ε-caprolactone) and poly(trimethylene carbonate)(PTMC) are attractive biopolymers to be used as biodegradable sutures, artificial skin, drug release system. It was known that PCL is a nontoxic biocompatible semicrystalline polymer with melting point of 63℃, and PTMC is an amorphous or little crystaline polymer. (omitted)

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.6
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• pp.451-458
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• 2009

Metallic bone plates and screws have been commonly used in oral and maxillofacial surgery for internal fixation. However, there are several disadvantages such as atrophy of cortical bone inherent to excessive rigid fixation systems, growth disturbance in growing individual, allergy reaction, interference with radiographic imaging, palpability, thermal sensitibity and the need for subsequent removal. To overcome these disadvantages and avoid additional surgery of removal of plates and screws, there have been many studies of biodegradable plates and screws. But, It also has complication such as foreign body reactions. We have undertaken a clinical and retrospective study on 140 patients in Dept. of Oral and Maxillofacial Surgery, Inha University Hospital from February 2006 to March 2009. The purpose of this study is to report the clinical cases and review of the literatures with biodegradable plates and screws. And we concluded following results. 1. 6 cases(3.4%) of the 177 operation sites(140 patients) experienced complications. 1 case(0.6%) was a failure of initial fixation, 1 case(0.6%) was a postoperative infection, 4 cases(2.3%) were inflammations or foreign body reaction. 2. Postoperative infections, inflammations and foreign body reactions were completely recovered with incision and drainage, supporative care with antibiotic coverage and removal of biodegradable plates. 3. Biodegradable plates and screws provide acceptable rigidity and stability clinically. But, long-term observation is required for the tissue reactions around the biodegradable plates and screws because of long resorption periods of the biodegradable materials.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.525-530
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• 1997

The changes in rheological properties of egg white stored in biodegradable package were investigated by pH change, failure stress and stress relaxation curve, and compared with control without package and complex PE. Initial pH of egg white stored in biodegradable package changed from 8.39 to 9.3 after 8 day storage, showing similar trend in pH change as that of control without package. Initial 14.25 N failure stress was changed into 6.76 N in biodegradable package and 9.31 N in control. Complex PE, having a relatively low gas permeability compared to biodegradable package, showed less pH changes from 8.30 to 8.81, but a greater decrease in failure stress into 5.29 N, indicating more deteriorating effect in complex PE package. Viscoelastic constants, such as elastic constant and viscous constant, obtained from stress-relaxation curve by three element Maxwell model were not significantly different between control and biodegradable package, but eggs stored in complex PE showed greater changes during storage. Therefore, the permeability seems to be the major factors to influence the rheological properties of egg and biodegradable packaging materials showed a potential substitute package for eggs.

• Proceedings of the Korea Society of Design Studies Conference
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• 2004.05a
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• pp.96-97
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• 2004