• Title/Summary/Keyword: Polyvinyl alcohol(PVA)

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Assessment of Formwork-Seepage Minimization in High Fluidity, Normal Strength Concrete Utilizing Thixotropic Properties (고유동 일반강도 콘크리트의 요변성 부여에 따른 거푸집 누출 저감 성능 분석)

  • Kim, Young-Ki;Lee, Yu-Jeong;Kim, In-Tae;Han, Dong-Yeop
    • Journal of the Korea Institute of Building Construction
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    • v.23 no.4
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    • pp.337-348
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    • 2023
  • The central objective of this study is to curtail the leakage of mortar or cement paste, often resultant of ill-constructed formwork, by implementing thixotropy in the formulation of high-fluidity, standard-strength concrete. When such concrete is utilized in smaller scale construction projects, instances of formwork gaps due to suboptimal construction precision may lead to significant leakage of mortar and paste, a problem not typically encountered with traditional slump-flow concrete. In this investigation, Polyvinyl Alcohol(PVA) and borax are incorporated into the concrete mixture to induce thixotropy. The experimental design includes varying methodologies for integrating PVA and borax, while assessing alterations in diverse concrete performances, including thixotropy and leakage reduction potential that simulates formwork gap conditions. Under the experimental conditions defined within this study, it was found that replacing, rather than merely adding PVA and borax, aids in averting water addition via suspensions. This approach yielded promising results in terms of concrete properties and proved efficacious in stemming leakage in concrete possessing sufficient thixotropy. Notably, when a 6% PVA suspension was substituted, a significant reduction in leakage was observed. Consequently, it is projected that construction quality can be ensured, even with lower precision formwork, by applying thixotropy to concrete through the use of PVA and borax.

Effect of protective colloid on the synthesis of Poly(Vinyl acetate-co-Ethyl acrylate) (Poly(VAc-co-EA) 공중합체 제조에 있어 보호콜로이드의 영향에 관한 연구)

  • Kim, Nam-Seok;Kim, Sung-Hoon
    • 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.

Changes of Characteristics of Low Temperature Plasma treated PVA Polarized Film (저온 플라즈마를 이용한 PVA 편광필름의 특성 변화)

  • Seo, Seung-Kyung;Jeun, Sang-Min;Koo, Kang
    • Proceedings of the Korean Fiber Society Conference
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    • 2003.10b
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    • pp.245-246
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    • 2003
  • 최근 정보통신 산업의 급속한 성장으로 평판 표시소자의 개발에 많은 관심이 모아지고 있다. 특히 이 중에서 액정 표시소자(LCD)의 수요는 급증하고 있으며 그에 관련된 부품 및 소재의 중요성 또한 강조되고 있다. LCD 부품 및 소재에서 가장 중요한 역할을 하는 편광필름은 일반적으로 PVA (polyvinyl alcohol) 또는 polyene 구조를 갖는 고분자 필름에 요오드를 염착시켜 사용되어 왔다. 본 연구에서는 PVA Film에 저온 플라즈마 처리를 함으로서 편광도와 투과도에 어떠한 영향을 미치는지에 대해 알아보고자 한다. (중략)

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Segregation resistance of high fluidity concrete depending on addition method of thixotropy-inducing materials (고유동 콘크리트의 고요변성 부여 물질 혼합방법에 따른 재료분리 방지 여부)

  • Kim, Young-Ki;Lee, Yu-Jeong;Heo, Jun-Ho;Han, Dongyeop
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.11a
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    • pp.113-114
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    • 2022
  • The aim of the research is to evaluate the segregation resistivity of the mixture conditions by changing the PVA and borax solutions for thixotropic property on concrete mixture. Since the water addition caused by producing solutions of PVA and borax induces segregation of the concrete mixture, the unit water was reduced by replacing the water amount for PVA and borax solution. By replacing the water from PVA and borax solutions, the segregation was prevented with prefixed concrete mix design and thixotropic properties were also occurred.

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Analysis of the Mechanical Properties of High-Tension Performance Biochar Concrete Reinforced with PVA Fibers Based on Biochar Cement Replacement Ratio

  • Kim, Sangwoo;Lee, Jihyeong;Hong, Yeji;Kim, Jinsup
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.44 no.5
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    • pp.603-613
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    • 2024
  • This study evaluated the mechanical properties of high-tension performance biochar concrete, focusing on the effects of varying biochar cement replacement ratios (0 %, 1 %, 2 %, 3 %, 4 %, and 5 %). Mechanical properties, including compressive strength, tensile strength, and flexural strength, were tested. The results showed a general decrease in compressive strength with increasing biochar replacement, with significant reductions at 1 % to 3 % levels. PVA fiber reinforcement improved long-term compressive strength, particularly at higher biochar levels. Tensile and flexural strength also showed initial reductions with low biochar levels but improved at higher replacement levels. PVA fibers consistently enhanced tensile and flexural strength. SEM images confirmed the integration of biochar and PVA fibers into the cement matrix, enhancing microstructural density and crack resistance.

Development of a New Process for PVA Degradation in Desize Wastewater by lmmobilized Symbiotic Bacteria (고정화 공생 Bacteria를 이용한 호발폐수 중 PVA분해 신공정 개발)

  • 김정목;조무환조윤래정선용
    • 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.

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A Study on the Engineering Characteristics of PVA (Polyvinyl Alcohol) Fiber-Cement-Soil Mixtures (PVA 시멘트 혼합토의 공학적 특성 연구)

  • Kim, Young-Ik;Yeon, Kyu-Seok;Kim, Ki-Sung;Yoo, Kyeong-Wan;Kim, Yong-Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.53 no.2
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    • pp.35-43
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    • 2011
  • This study aimed to investigate the engineering characteristics of PVA fiber-cement-soil mixture used to prevent or reduce brittle failure of cement-soil mixtures due to the tensile strength increase from the addition of a synthetic fiber. The engineering characteristics of PVA fiber-cement-soil mixtures composed of PVA fiber, soil, and a small amount of cement was analysed on the basis of the compaction test, the unconfined compression test, the tensile strength test, the freezing and thawing test, and the wetting and drying test. The specimens were manufactured with soil, cement and PVA fiber. The cement contents was 2, 4, 6, 8, and 10%, and the fiber contents was 0.4, 0.6, 0.8, and 1.0% by the weight of total dry soil. To investigate the strength characteristics depending on age, each specimen was manufactured after curing at constant temperature and humidity room for 3, 7 and 28 days, after which the engineering characteristics of PVA fiber-cement-soil mixtures were investigated using the unconfined compression test, the tensile strength test, the freezing and thawing test, and the wetting and drying test. The basic data were presented for the application of PVA fiber-cement-soil mixtures as construction materials.

Degradation of Polyvinyl Alcohol in Dye-Processing Wastewater by Agar-Acrylamide Microbial Immobilization Method (한천-아크릴아마이드 미생물 고정화법에 의한 폐수 중 폴리비닐알콜의 분해)

  • 김재훈;김정목조무환
    • KSBB Journal
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    • v.10 no.3
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    • pp.241-248
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    • 1995
  • For the treatment of poorly biodegradable polyvinyl alcohol(PVA) in dye-processing wastewater, immobilized microbial beads were prepared by uslng agar-acrylamide method. PVA removal efficiency for the synthetic wastewater was 85% at the PVA volume loading rate of $3.1g/\ell$.day. In case of real desizing wastewater, PVA removal efficiency was 81.3% at the PVA volume loading rate of $3.25g/\ell$.day. In observation of cross section of immobilized bead passed 5 months with diameter of 2.4mm, the growth of cell was limited by the resistance of substrate and oxygen transfer for the inners region of more than 48% of bead radius from the surface. It was estimated that 70% of total removed PVA was degraded by the immobilized cells in the continuous immobilized reactor. Substrate utilization rate in the suspended reactor was decreased with increasing dilution rates above 0.083 hr-1, but that in the immobilized reactor was increased with increasing dilution rates up to 0.125hr-1. The substrate removal efficiency of immobilized reactor was much superior to that of suspended reactor with increasing dilution rates. Saturation constant of substrate utilization rate equation, Ks was $6.6 g PVA/\ell$, and maximum specific substrate utilization. k was 0.175g PVA/g cell.hr

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A new Insolubilizer Development to Enhance the Water Resistency of Corrugated Paper and its Apply Methods Evaluation (골판지의 내수성 향상을 위한 내수화제 개발과 적용방법 평가)

  • Shin, Jun-Seop
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.7 no.1
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    • pp.1-8
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    • 2001
  • This study was carried out to develop a new insolubilizer for water resistency enhancement and to evaluate its optimum apply method to corrugated paper. The addition of polyvinyl alcohol(PVA) backbone polymer to conventional starch glue caused a poor dispersibility, but flavonoid resin addition showed a good runnability and water resistency. The double coatings(top & under) of water-proof chemicals to corrugating liner made even better the water resistency of corrugating paper. This study suggested that water-proof chemical treatments be an effective method in water-resistant corrugating paper manufacturing for a cold chain system.

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Synthesis of Size Controllable Silk Fibroin Microparticles and Their Stability on Different Solutions

  • Aryal, Susmita;Yu, Chan Yeong;Cho, Hyeyoun;Choi, Seung Ho;Key, Jaehong
    • Journal of Biomedical Engineering Research
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    • v.43 no.4
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    • pp.251-258
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    • 2022
  • Silk fibroin microparticles were fabricated using a phase separation technique between silk fibroin solution and polyvinyl alcohol. We found that the concentration of polyvinyl alcohol determines the size of microparticles. The mean diameter of the silk fibroin microparticles varied from 3.48 ㎛ to 4.05 ㎛. The silk fibroin microparticle size increased as a function of the concentration of PVA in aqueous silk solution. The resulting silk fibroin microparticles have narrow size distribution (i.e. monodisperse) and smooth/spherical surface. Also, we studied the effects of mouse serum, sodium phosphate buffer (PBS), and pH on the stability of the silk fibroin microparticles. Overall, we demonstrated the simple method to fabricate and to control the silk fibroin microparticles that makes our silk microparticles to be usable for a potential drug delivery carrier.