• KSBB Journal
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• v.21 no.1 s.96
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• pp.54-58
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• 2006

The purpose of this study is to search the characteristics of PVA degrading enzymes which were obtained from Microbacterium barkeri KCCM 10507 and Paenibacillus amylolyticus KCCM 10508, respectively. As a result of the PVA degrading test using crude enzymes, the activity of SAO (secondary alcohol oxidase) was maximized after 2 or 3 days from start of the test, while the activity of BDH (${\beta}$-diketone hydrolase) was gradually increased during the test. Activities of them were maintained in the presence of PVA, but as PVA was gradually degraded, their activity was decreased. PVA was inoculated again into the media, their activity was revealed. This result indicated that above two different enzymes were closely connected with PVA degradation and PVA was degraded by activity of SAO and BDH. Maximum activity of them was 1.5-1.8 unit for SAO and 1.5-2.0 unit for BDH under $35^{\circ}C$ and pH 7.8-8.8, respectively.

• KSBB Journal
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• v.6 no.4
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• pp.395-402
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• 1991

A new process was developed to degrade PVA(polyvinyl alcohol) in desize wastewater. Two symbiotic bacteria of Pseudomonas strain G5Y and PW were immobilized on the media by adsorption. A natural zeolite was chosen as the best media considering cell adhesion capacity, sedimentation rate, and material cost. PVA and COD removal efficiencies of this system for synthetic wastewater were 84% and 85% at the retention time of 6 hr, when the volumetric loading rate was PVA 8g/L·day and COD 8g/L·day, and cell density was 19,775 mg/L. In case of desire wastewater, they were 78% and 72% at the retention time of 6 hr, respectively, when the volumetric loading rate was PVA 8g/L·day and COD 13.2g/L·day, and cell density was 32,899mg/L. In case of desize wastewater, PVA and COD removal efficiencies were lower than synthetic wastewater, but cell density of the desize wastewater was lower than that of the synthetic wastewater, because there were insufficiency of necessary nutrition and variety of desize materials in the desize wastewater. A pilot test was successfully performed showing 88% and 82%, PVA and COD removal efficiencies at the retention time of 24 hr, when volumetric loading rate were 4.7 PVA g/L·day and COD 6.9g/L·day, and cell density was 12,,324 mg/L.

• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.241-244
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• 2004

Radiation treatment with gamma-rays and electron-beams was used to remove polyvinyl alcohol(PVA), one of the main components of dyeing wastewater. PVA was effectively decomposed by radiation treatment, thus the removal was near 100 % at an initial PVA concentration of 44 mg/L. However, total organic carbon(TOC) removal was less than 5 % due to lower transformation of PVA to $CO_2$. This directly indicates the radiation treatment alone is not appropriate for the complete decomposition of PVA. In this sense, the improvement of biodegradability($BOD_5/COD$) of PVA by radiation treatment was studied. Both gamma-ray and electron-beam treatments significantly increased the biodegradability of PVA by transforming non-biodegradable PVA to biodegradable by-products. This suggests radiation treatment, especially electron-beam treatment that showed better improvement of biodegradability, can be used as a pre-treatment of biological degradation process of PVA.

• Journal of the Korean Applied Science and Technology
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• v.15 no.3
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• pp.21-26
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• 1998

Polyvinyl alcohol[PVA] is useful for the production of water-soluble packaging, paper, textile sizes. PVA and Chitosan are known as biodegradable polymers. PVA/chitosan blend films were prepared by solution blends method in the weight ratio of chitosan for the purpose of useful biodegradable films. Thermal and mechanical properties of PVA/chitosan blend films such as DSC, impact strength, tensile strength and morphology by SEM were determined. As a result, The ratio of 10.0wt% PVA/chitosan blend films were similar to PVA. Blend films were completely degraded pH 4.0 better than 7.0, 10.0 in the buffer solution. Also, Blend films were rapidly degraded enzyme(${\beta}-glucosidase$) solution better than pH solution by Enzymolysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.191-191
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• 2007

By employing a photo-sensitive PVA as a photoresist, we first demonstrated simultaneous patterning and passivation of P3HT active layer. The passivation layers were obtained by annealing the organic layers after developing PVA and over-etching the P3HT layer. The fabricated OTFTs were electrically characterized. The OTFTs after the passivation exhibited the field-effect of ${\sim}5.9{\times}10^{-4}cm^2/V{\cdot}s$, on/off current ratio of ${\sim}10^3$. The value of OTFTs a little degradation with time in air but it appeared different unpassivated OTFT.

• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.216-221
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• 2010

Polyvinyl acetate (PVAc) prepared by emulsion polymerization has broad applications for additive such as paint binder, adhesive for wood and paper due to its low glass transition temperature which help to plasticize substrate resins. Since emulsion polymerization has a disadvantage that surfactant and ionic initiator degrade properties of the product polymer, poly (vinyl acetate-eo-ethyl acrylate) (VAc-EA) was synthesized using potassium persulfate as catalyst and polyvinylalcohol (PVA) as protective colloid to prevent the degradation. The copolymer latex product was internally plasticized and has enhanced adhesion, water resistance during VAc-EA emulsion polymerization. No coagulation and complete conversion occur with the reactant mixture of 10 mmol/L potassium persulfate, 10 mmol/L poly ( vinyl alcohol) (PVA 17). As the concentrations of PVA increase, the viscosity becomes increase.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.636-642
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• 2013

In order to overcome drawbacks (i.e., filtration and recovery) of conventional powder type photocatalysts, nano-ZnO/Laponite/PVA (ZLP) photocatalyzed adsorption balls were developed by using in situ mixing of nanoscale ZnO as a photocatalyst, and Laponite as both adsorbent and supporting media in deionized water, followed by the poly vinyl alcohol polymerization with boric acid. The optimum mixing ratio of nano-ZnO:Laponite:PVA:deionized water was found to be 3:1:1:16 (by weight), and the mesh and film produced by PVA polymerization with boric acid might inhibit both swelling of Laponite and detachment of nanoscale ZnO from ZLP balls. Drying ZLP balls with microwave (600 watt) was found to produce ZLP balls with stable structure in water, and various sizes (55~500 ${\mu}m$) of pore were found to be distributed based on SEM and TEM results. In the initial period of reaction (i. e., 40 min), adsorption through ionic interaction between methylene blue and Laponite was the main removal mechanism. After the saturation of methylene blue to available adsorption sites for Laponite, the photocatalytic degradation of methylene blue occurred. The effective removal of methylene blue was attributed to adsorption and photocatalytic degradation. Based on the results from this study, synthesized ZLP photocatalyzed adsorption balls were expected to remove recalcitrant organic compounds effectively through both adsorption and photocatalytic degradation, and the risks of environmental receptors caused by detachment of nanoscale photocatalysts can be reduced.

• Microbiology and Biotechnology Letters
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• v.25 no.1
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• pp.89-95
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• 1997

The current processer of the textile wastewater treatment are mostly consisted of a combination of a physico-chemical and a biological treatment. The overall efficiency of these processes is, however, assessed to be fairly low. It is even worse during the summer season when temperature of the wastewater rises above 40$\circ $C. Therefore, a feasible process of the textile wastewater treatment which can work efficiently at higher temperatures was investigated in this work. We used a bench scale reactor consisted of one 4 liter anaerobic and one 8 liter aerobic tank, and the thermophilic symbiotic PVA degraders, Pasteruella hemolytica KMG1 and Pseudomonas sp. KMG6 that had been isolated in our laboratory. In the preliminary flask experiments, we observed that the thermophilic symbiotic PVA degraders could not grow in the wastewater substrate. Then, we isolated the mutant strains by acclimating the KMG1and KMG6 strains to the wastewater medium. The mutant symbionts (KMG1-1 and KMG6-1) were isolated through 6 times successive transfers into the fresh wastewater medium after 5 days culture for each. The mutant strains obtained grew well in the mixed medium composed of 75% wastewater and 25% synthetic medium, and supplemented with 0.5% PVA as a sole carbon source. During the culture for 14 days at pH 7.0 and 40$\CIRC $C, the bacteria assimilated about 89% of the added PVA. The symbionts degraded equally well all the PVA substrates of different molecular weight (nd=500~30000). In contrast to the flask experiments, in the reactor system the mutant strains showed very low levels of the PVA and COD removal rates. However, the new reactor system with an additional aerobic tank attained 82% removal rate of COD, 94% of PVA degradation and 71% of color index under the conditions of 5% inoculm on the tank 2, incubation temperature of 40$\circ $C, dissolved oxygen level of 2~3 mg/l and retention time of 30 hours. This result ensures that the process described above could be an efficient and feasible treatment for the PVA contained textile wastewater at higher temperatures.

• Polymer(Korea)
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• v.26 no.2
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• pp.168-173
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• 2002

Poly (vinyl butyral) (PVB) was synthesized by acetalization of poly (vinyl alcohol) (PVA) PVB was prepared in particulate forms in water, and chemical and physical properties of the products were characterized using various techniques. The prepared PVB had size distribution from 100 to 700 $\mu\textrm{m}$ with mean diameter of about 380 $\mu\textrm{m}$. The chemical structure of PVB was characterized using FT/IR and NMR, and the average degree of acetalization was determined to be 77% from the titration measurement. DSC data showed that the crystalline structure of PVA vanished as acetalization reaction proceeded to produce PVB, and the glass transition temperature emerged at about $70^{\circ}C$. TGA data showed that PVB was much more thermally stable than PVA, and showed no degradation up to $300^{\circ}C$. Solubility test showed that PVB was soluble in alcohols but Insoluble in water, being totally different from PVA.

• Biomaterials and Biomechanics in Bioengineering
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• v.4 no.1
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• pp.1-8
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• 2019

The aim of this study was to investigate the effect of total polymer concentration on the chemical structure, morphology of pores, porosity, swelling ratio, degradation of gelatin-poly (vinyl alcohol) (Gel-PVA) cryogel scaffolds. Porous cryogels were prepared with cryogelation technique by using glutaraldehyde as a crosslinker. Functional group composition of cryogels after crosslinking was investigated by Fourier Transform Infrared (FTIR). The morphology of cryogels was characterized via scanning electron microscopy (SEM) and porosity analysis. All of the cryogels had a porous structure with an average pore size between $45.58{\pm}14.28$ and $50.14{\pm}4.26{\mu}m$. The cryogels were biodegradable and started to degrade in 14 days. As the polymer concentration increased the swelling ratio, the porosity and the degradation rate decreased. Spongy and mechanically stable Gel-PVA cryogels, with tunable properties, can be potential candidates as scaffolds for tissue engineering applications.