• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.928-933
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• 2001

Approximately 0.1 mg/ml of polyvinyl alcohol (PVA) was degraded by the growing cell, Brevibacillus laterospours, for 30 h, and 0.2 mg/ml of PVA was degraded by the cell-free extract that was isolated from Brevibacillus laterosporus. Approximately $0.29{\mu}g$/ml of acetic acid was produced from PVA by using the cell-free extract as a catalyst for 40 min. $V_{max}\;and\;K_m$ value of purified PAV-degradation enzyme was 3.75g/l and 2.75 g/l/min in reaction with EDTA and 3.99 g/l and 2.98 g/l/min in reaction without EDTA, respectively. Molecular weight of the purified enzyme determined by SDS-PAGE was 63,000 Da. Alcohol dehydrogenase and aldehyde dehydrogenase activities were qualitatively detected on a native acrylamide gel by an active staining method, indicating the existence of the metabolic pathway to use PVA as a substrate.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.11
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• pp.815-820
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• 2013

The purpose of this research is to prepare the aluminum electrode coated with activated carbon for removing air pollution dust. The experiments were studied on the selection of optimal polymer for binding aluminum plate with powdered activated carbon, preventing the pore blocking of activated carbon from polymer binder, and the dust treatability for the prepared activated carbon electrode. The optimal adhesive for coating activated carbon on an electric aluminum plate was polyvinyl acetate (PVA) with vinyl functional group. For the opening of the blocked pore with polymer, it was very effective to embed polymer solvent in pore of activated catbon firstly before mixing activated carbon with PVA, and then to devolatilize the embedded solvent of carbon pore at high temperature. The mass of trapped dust on aluminum electrode coated with activated carbon was about double of the trapped one on just aluminum electrode.

• 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 the Korean Ceramic Society
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• v.28 no.7
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• pp.509-516
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• 1991

The effect of various polymers on the freeze-thaw resistance of hardened cement mortar was investigated. For this study, styrene butadiene rubber (SBR), ethylene vinyl acetate (EVA), polyvinyl alcohol (PVA) were used to prepare cement mortar specimen, and then freeze-thaw experiment was carried out. By adding SBR adn EVA to the specimen, the freeze-thaw resistance of specimens was improved, but when PVA was added to the specimen, its freeze-thaw resistance was lowered. Particularly, the specimens which were added 5, 10% of SBR and 5% of EVA showed excellent freeze-thaw resistance in the salt environment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.102-112
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• 2019

This paper studies impact fracture behavior under temperature variation and compressive flexural strength of cement composites using VAE(vinyl acetate ethylene) powder polymer and PVA(polyvinyl alcohol) fiber. Impact test were conducted in the temperature range selected for the $-35^{\circ}C$, $0^{\circ}C$ and $35^{\circ}C$. In this experimental study, impact test were carried out using a drop impact testing machine (Ceast 9350) to obtain such as displacement, time, and impact fracture energy of normal specimen and and cement composites specimen. As test results, the use of VAE powder polymer and PVA fiber were observed to enhance the flexural strength of mortar. The compressive strength of PVA fibers reinforced cement composites was slightly decreased at 28 days, but the flexural strength was observed to increase 24.4% of normal mortar strength. As a result of the drop impact tests, PVA fiber reinforced cement composites specimens showed microcracks due to energy dispersion and crack prevention with bridge effect of the fibers, and scabbing or perforation by impact was suppressed. On the other hand, the normal mortar and VAE powder polymer cement composites specimens were carried out to the perforation and macro crack. Most of normal mortar and the cement composites subjected to impact load on specimens shows mostly local brittle failure. The impact resistant performance of the specimen with PVA fiber was greatly improved due to the increase of flexure performance.

• Composites Research
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• v.21 no.1
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• pp.40-45
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• 2008

Rubber hose assembly for automotive hydraulic brake during operation is subject to combined stresses of cyclic pressure, cyclic bending and torsion as well as thermal load. The rubber hose is composed of ethylene-propylene diene monomer(EPDM) rubber layers reinforced by polyvinyl acetate(PVA) braided fabrics. A durability tester with loading rigs for inducing the above cyclic stresses was used to investigate failure mechanisms in the rubber hose assembly. Failure examination was performed at every 100 thousands cycles of bending and torsion. Hose samples were sectioned with a diamond-wheel cutter and then polished. The polished surface was observed by optical microscope and scanning electron microscope (SEM). Some interfacial delamination with a length of about 1mm along the interface between EPDM rubber and PVA fabrics was shown at the test cycles of 400,000. The delamination induced some cracking into the outer rubber skin layer to leading the final rupture of the hose.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.253-253
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• 2009

Electrospinning is one of the simple, cost- efficient methods to produce long continuous semiconducting oxide nanofibers. Polyvinyl Alcohol (PVA) and zinc acetate were used. PVA/Zinc acetate aqueous solutions were electrospun into nonwoven webs. CCD camera, with a lens of long working distance and digital video board were used in capturing the drop and web deposition. The diameter and morphology of nanofibers were analyzed with a Field-emission scanning electron microscopy (FE-SEM). In this study, the average diameter and morphology of nanofibers have been explorered.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3733-3737
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• 2013

Polyacrylonitrile (PAN)-based ultrafine fibers and carbon fibers were produced by wet-spinning, and the crystal sizes and thermal and mechanical properties of the fibers were investigated. Scanning electron microscopy revealed that the superfine fibrils in the surfaces of the PAN/polyvinyl acetate (PVA) blend fibers increased slightly with increasing PAN content before removal of the PVA. Differential scanning calorimetry indicated that the PAN and PVA in the blend fibers do not mix and, therefore, each maintains their inherent thermal characteristics. The crystal sizes of the blend fibers prepared by removing PVA with water increased at 5 wt % water. The extent of the reaction of the PAN carbon fibers, as calculated from the FT-IR spectra, is maximized at the stepwise temperature of $230^{\circ}C$, and the density increased significantly above this temperature. The carbon fibers had relatively good mechanical properties, as shown by their tensile strength and modulus values of 2396 MPa and 213 GPa, respectively.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.745-752
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• 1994

A polymer reinforced grouts using ordinary portland cement mortar and water soluble polymer{polyvinyl alcohol(PVA), styrene-butadiene rubbre(SBR), etylene-vinyl acetate copolymer(EVA)} were made. The mechanical properties of the hardened specimens were investigated through the observation of the microstructure and application of fracture mechanics. When the PVA, SBR and EVA was added with 1.5 wt% to the grouts, the compressive strength were about 54 MPa, 63 MPa and 68 MPa respectively, and the flexural strength was about 11 MPa, 12.8 MPa, and 13.6 MPa respectively, and Young's modulus was about 3.8 GPa, 4.4 GPa and 4.6 GPa respectively, and critical stress intensity was about 0.73 MNm-1.5, 0.85 MNm-1.5 and 0.9 MNm-1.5 respectively. It can be considered that the strength improvement of polymer mortar grouts may be due to the removal of macropores and the increase of various fracture toughness effects, such as grain bridging, frictional interlocking and polymer bridging.

• Journal of the Korea Furniture Society
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• v.11 no.1
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• pp.25-29
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• 2000

This study was carried out to analyze the ultrasonic properties of sound board which was glued with various adhesives and to evaluate which adhesive is the best for the acoustic radiation of the musical instrument. The results are as follows: 1. Animal glue is the best adhesive for the sound board with respect to the acoustic radiation ratio of the musical instruments. Epoxy resin and polyvinyl acetate resin are the next group, urea formaldehyde resin and Hot melt are the third group, polychloroprene(CR) resin is the lowest. 2. Epoxy resin, animal glue and Titebond(PVA) give the highest shear strength and the highest wood failure relatively Hot melt and polychloroprene(CR) resin do not meet the standard because of low wood failure.