• Proceedings of the Korean Fiber Society Conference
• /
• 1997.04a
• /
• pp.328-332
• /
• 1997

Hot stretching focused on the improvement of properties of poly(L-lactic acid) fiber. Some aliphatic polyesters are biodegradable under microbial attack and the new unique applications are expected. Generally, these materials have a somewhat low melting temperature and low mechanical properties compared with the aromatic polyesters. In this study, melt-spinning of poly(L-lactic acid) was conducted. We investigated effects of the stretching and the molecular orientation of aliphatic polyester fibers on the change of fine-structure. Glass transition temperature, molecular orientation and crystallinity increased according to the increase of stretching ratio.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2008.04a
• /
• pp.19-21
• /
• 2008

The quinolone antibiotics Ciprofloxacin shows broad antimicrobial spectrum, heat stability, limited water solubility, and similar structure and size to disperse dyes. The object of this study is to develop the infection-resistant medical extile material by applying Ciprofloxacin to a series of polyester materials such as PET, PDO, PLA, and PGA. All the Ciprofloxacin compound polyester materials demonstrated the superior antimicrobial activity to the organisms S. aureus and E. coli.

• Journal of Environmental Health Sciences
• /
• v.23 no.3
• /
• pp.85-90
• /
• 1997

The objective of this study was to investigate biodegradation of TPA(terephthalic acid) and EG (ethylene glycol), treatment efficiency of polyester weight loss wastewater and microbial characteristics by aerated submerged biolfilm(ASB) p.rocess. In a batch reactor, pH increased from 7.0 to 8. 5 in the biodegradation of TPA. Whereas, in case of EG, decreased from 7.0 to 5.2. COD concentration rapidly decreased within 24hr in the biodegradation of TPA and EG. COD removal velocity constant(k) were 0.065-0.088 hr$^{-1}$. The biodegradation velocity of TPA was 1.4 times faster than that of EG. The ratio of suspended biomass to the total biomass in the reactor was 18.3-33.3%, increased as a high ratio of EG content. Biofilm thickness, biofilm dry density and attached biomass were 346-432 $\mu$m, 41.8-61.9 mg/cm$^3$, 1.45-2.67 mg/cm$^2$, respectively. There values increased as a high ratio of TPA content. In the hydraulic retention time of 36 hr, organic loading rate of 4 kgCOD/m$^3\cdot$ day and packing ratio of 70%, the effluent concentrations of TCOD, SCOD in a continuous flow reator were 1,388 mg/l, 147 mg/l and removal efficiencies were 77%, 97.6%, respectively.

• Macromolecular Research
• /
• v.12 no.4
• /
• pp.374-378
• /
• 2004

The biodegradable and biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a copolymer of microbial polyester, was fabricated as nanofibrous mats by electrospinning. Image analysis of the electrospun nanofibers fabricated from a 2 wt% 2,2,2-trifluoroethanol solution revealed a unimodal distribution pattern of fiber diameters with an observed average diameter of ca. 185 nm. The fiber diameter of electrospun fabrics could be controlled by adjusting the electro spinning parameters, including the solvent composition, concentration, applied voltage, and tip-to-collector distance. Chondrocytes derived from rabbit ear were cultured on a PHBV cast film and an electrospun PHBV nano-fibrous mat. After incubation for 2 h, the percentages of attached chondrocytes on the surfaces of the flat PHBV film and the PHBV nanofibrous mat were 19.0 and 30.1 %, respectively. On the surface of the electrospun PHBV fabric, more chondrocytes were attached and appeared to have a much greater spreaded morphology than did that of the flat PHBV cast film in the early culture stage. The electro spun PHBV nanofabric provides an attractive structure for the attachment and growth of chondrocytes as cell culture surfaces for tissue engineering.

• Journal of Environmental Science International
• /
• v.11 no.12
• /
• pp.1315-1320
• /
• 2002

Since the enzymatic degradation of microbial poly[(R)-3-hydroxybutyrate-co-3-hydroxyvalerate] (P(3HB-co-3HV)) initially occurs by a surface erosion process, a degradation behavior could be controlled by the change of surface property. In order to control the rate of enzymatic degradation, plasma gas discharge and blending techniques were used to modify the surface of microbial P(3HB-co-3HV). The surface hydrophobic property of P(3HB-co-3HV) film was introduced by CF$_3$H plasma exposure. Also, the addition of small amount of polystyrene as a non-degradable polymer with lower surface energy to P(3HB-co-3HV) has been studied. The enzymatic degradation was carried out at 37 $^{\circ}C$ in 0.1 M potassium phosphate buffer (pH 7.4) in the presence of an extracellular PHB depolymerase purified from Alcaligenes facalis T1. Both results showed the significant retardation of enzymatic erosion due to the hydrophobicity and the enzyme inactivity of the fluorinated- and PS-enriched surface layers.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.4 no.1
• /
• pp.33-40
• /
• 1997

The microbial growth of fresh, vacuum packaged, cook-in-bag uncured beef patties was determined in two film structures, a commercial (PE/EVOH), and super barrier ($SiO_2$ coated polyester) material. Packaged samples were cooked to internal temperature of 71 and $82^{\circ}C$ for 30 minutes, and stored in temperature abused ($23{\pm}2^{\circ}C$) and refrigerated storage ($4-6^{\circ}C$). Barrier properties had a significant effect (p<0.001) on aerobic and mesophilic growth in the abused condition. Cooking temperatures had a statistically significant effect (p<0.05) on aerobic growth in the refrigerated condition. The growth of anaerobes and psychrophiles were not significantly effected by either variables. Storage times had the most significant effect (p<0.001) for all groups of microorganisms. The physical properties of the commercial film (strength, thickness, and shrinkage) were changed after exposure to thermal treatment, while the super barrier package had actually no change.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.12
• /
• pp.2171-2178
• /
• 2016

Polyester cloth (PC) was selected as a prospective inexpensive substitute separator material for microbial fuel cells (MFCs). PC was compared with a traditional Nafion proton exchange membrane (PEM) as an MFC separator by analyzing its physical and electrochemical properties. A single layer of PC showed higher mass transfer (e.g., for $O_2/H^+/ions$) than the Nafion PEM; in the case of oxygen mass transfer coefficient ($k_o$), a rate of $50.0{\times}10^{-5} cm{\cdot}s^{-1}$ was observed compared with a rate of $20.8{\times}10^{-5}cm/s$ in the Nafion PEM. Increased numbers of PC layers were found to reduce the oxygen mass transfer coefficient. In addition, the diffusion coefficient of oxygen ($D_O$) for PC ($2.0-3.3{\times}10^{-6}cm^2/s$) was lower than that of the Nafion PEM ($3.8{\times}10^{-6}cm^2/s$). The PC was found to have a low ohmic resistance ($0.29-0.38{\Omega}$) in the MFC, which was similar to that of Nafion PEM ($0.31{\Omega}$); this resulted in comparable maximum power density and maximum current density in MFCs with PC and those with Nafion PEMs. Moreover, a higher average current generation was observed in MFCs with PC ($104.3{\pm}15.3A/m^3$) compared with MFCs with Nafion PEM ($100.4{\pm}17.7A/m^3$), as well as showing insignificant degradation of the PC surface, during 177 days of use in swine wastewater. These results suggest that PC separators could serve as a low-cost alternative to Nafion PEMs for construction of cost-effective MFCs.

• Proceedings of the Korean Fiber Society Conference
• /
• 2001.10a
• /
• pp.199-202
• /
• 2001

현재 플라스틱에 의한 환경오염이 사회문제로까지 확대되면서 이를 해결하기 위한 한가지 대책으로 분해성 플라스틱의 개발이 절실히 요구되어 전세계적으로 많은 연구가 이루어지고 있다. 생분해성을 가지는 미생물 폴리에스테르 중에서 가장 대표적인 poly(3-hydroxybutyrate), PHB는 우수한 역학적 성질을 가지며, 또한 천연고분자 중에서 융점을 가지는 유일한 열가소성 재료이다. (중략)

• Journal of Environmental Science International
• /
• v.22 no.2
• /
• pp.243-249
• /
• 2013

Fibers of microbial polyesters, poly(3-hydroxy butyrate) (PHB) and poly(3-hydroxy butyrate-co-3-hydroxy valerate) (HB-co-HV) were prepared by electrospinning method. The obtained fibers were evaluated by differential scanning calorimetry, scanning electron microscopy, and oil absorption. The formation of fibers was strongly dependent on a concentration of solution. At a low concentration, the fibers contained beads which is from aggregation of polymer due to short evaporation time. The fine fibers with $2-5{\mu}m$ diameter were obtained at 20 wt% concentration. The contact angle measurement showed that the fiber had higher water contact angle than the film due to the lotus-like effect. Oil absorbency showed that the fiber had higher than the film. Specially, the HB-co-HV fiber which was spinned from 20 wt% absorbed 65% oil which is much higher than that of a normal polypropylene-based oil paper.

• Korean Journal of Food Science and Technology
• /
• v.47 no.2
• /
• pp.224-232
• /
• 2015

The effects of cold plasma (CP) treatments on the physicochemical and biodegradable properties of a corn biomass-containing polyester (CBPE) film were studied. The CBPE film was treated with CP generated by $N_2$, $O_2$, He, Ar, or dry air at 400-900 W and 667 Pa for 10-40 min. The glass transition temperature of the CBPE film ($-30.2--28.6^{\circ}C$) was not affected by the CP treatment, while the elastic modulus and water vapor permeability decreased (p<0.05). The ink printability was improved by the treatment and the improved printability was maintained during storage for 56 days at room temperature. Roughness of the film increased after treatments and the level of roughness appeared to increase during storage. Heat and microbial biodegradability of the CBPE film was improved by the air-CP treatment (p<0.05). These results have demonstrated the potential of applying CP treatments to improve the flexibility, printability, and biodegradability of CBPE films.