• Composites Research
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• 제27권1호
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• pp.19-24
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• 2014

본 연구에서 아마/비닐에스테르(Flax/vinyl ester)를 적용한 친환경 구조물 설계를 위한 선행 연구로서 아마/비닐 에스테르 자연 섬유 복합재료의 기계적 물성치를 분석하였다. 시편 제작을 위해 VARTM 제작 공법이 적용되었다. 참고문헌에서 제시한 자연 섬유 복합재료의 물성치와 본 연구에서 제작된 시편의 물성치를 비교하였다. 이 결과를 바탕으로 아마/비닐 에스테르 복합재료가 친환경 구조물에 적용하는 것이 유리함을 확인하였다.

• Composites Research
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• 제12권6호
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• pp.15-21
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• 1999

비닐에스테르 수지와 탄소섬유의 계면접착력 향상을 위하여 탄소섬유에 물에 분산된 carboxy modified poly(hydroxy ether) (C-PHE)와 수용성 고분자인 poly(hydroxy ether ethanol amine) (PHEA) 및 비수용성인 poly(hydroxy ether) (PHE) 로 코팅하였다. 고분자로 코팅된 탄소섬유와 수지의 계면전단강도는 micro-droplet 시편을 제조하여 측정하였으며,각 시료마다 30개 이상의 시편을 사용하였다. 접착기구 규명을 위하여 코팅재로 사용된 고분자와 비닐에스테르 수지와 계면에서 확산현상을 고찰하였으며, 접착성 시험 후 탄소섬유의 표면을 SEM을 이용하여 분석하였다. PHE와 C-PHE코팅으로 탄소섬유의 계면전단강도가 크게 증가하였으며, 이는 이들 고분자의 비닐에스테르에 대한 우수한 용해도(solubility)때문으로 보여진다. 하지만 용해도가 낮은 PHEA코팅은 접착력 향상에 효과가 없었다.

• 방사선산업학회지
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• 제4권1호
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• pp.19-23
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• 2010

Vinyl ester (VE) resins, introduced in the late 1960s, have made large strides in reinforced plastics applications as adhesive and matrix materials on their appropriate mechanical performance characteristics in the glassy state. Generally, VE resins are a group of dimethacrylate resins based on bisphenol A type epoxy resin. They exhibit easy handling properties as well as good resistance to most chemical agents due to their mechanical and thermal properties. In this study, the effects of curing methods of vinyl ester resins on gel contents, flexural strength and dynamic mechanical properties were investigated. Thermal curing (room temperature, $80^{\circ}C$) and electron beam curing were used to crosslink a VE resin/styrene complex (65/35 wt%) with methyl ethyl ketone peroxide (MEKPO) as a catalyst and an 8 wt% cobalt naphthenate in styrene solution as a accelerator. For the samples, gel contents as well as flexural strength and dynamic mechanical properties were characterized and compared by soxhlet apparatus, universal testing machine (UTM) and dynamic mechanical analysis (DMA). As a result, the electron-cured VE resin was confirmed as a better condition than those for gel contents, flexural strength and dynamic mechanical properties, respectively.

• Composites Research
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• 제30권5호
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• pp.303-309
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• 2017

Organo-montmorillonite (OMMT) has attracted much attention for fiber-reinforced polymer composites as a filler material due to high aspect ratio and low charge density. The present study focused on the fabrication of nanocomposites using Vinyl ester and Jute fabric as matrix and reinforcement respectively. The OMMT was uniformly dispersed in vinyl ester resin at 1, 2 and 3 wt%, loading through high speed mechanical stirrer at room temperature and further nanocomposites were manufactured through vacuum assisted resin infusion (VARI) technique. Effects of OMMT on the mechanical properties of vinyl ester/Jute composites were carefully investigated through tensile, bending and Izod impact tests, which revealed significant improvement in mechanical properties. The morphology of the nanocomposites after tensile test was investigated by SEM which affirmed that OMMT filled nanocomposites has improved interactions with the host matrix than the pure composites. Based on the nature and flame retardancy mechanism, the OMMT slightly improved the flammability property which was clearly explained by horizontal burning test.

• Elastomers and Composites
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• 제53권1호
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• pp.1-5
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• 2018

In the current research, the curing kinetics of a mixture system consisting of a Bisphenol-A type vinyl ester resin and styrene monomer was studied. Methylethylketone peroxide and cobalt octoate were used as the polymerization initiator and accelerator respectively. Thermograms with several different heating rates were obtained using non-isothermal differential scanning calorimetry. Activation energy values analyzed by the Flynn-Wall-Ozawa isoconversional method showed a three-step change with conversion ${\alpha}$: a slight decrease initially for ${\alpha}$ < 0.1, a constant value of 47.9 kJ/mol in the range 0.1 < ${\alpha}$ < 0.7, and a slow increase for 0.7 < ${\alpha}$. When assuming a constant activation energy of 47.9 kJ/mol, an autocatalytic model of the Sestak-Berggren equation was considered as the proper mathematical model of the conversion function, indicating an overall order of 1.2.

• 유기물자원화
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• 제13권3호
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• pp.97-104
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• 2005

본 연구에서는 폴리에스테르 비닐과 고밀도 폴리에틸렌(HDPE)의 분해에서 수분 함량, pH, 연소시 무게에 대하여 조사하였다. 폴리에스테르 비닐은 30일 동안의 음식물 쓰레기의 미생물에 의하여 분해가 이루어졌으나, 고밀도 폴리에틸렌(HDPE)은 분해가 전혀 이루어지지 않았다. 폴리에스테르계 생분해성 비닐은 음식물의 미생물에 의하여 10일후에 급속하게 분해가 일어났으며, 그 결과 무게가 감소함을 나타내었다. 연소반응의 $300^{\circ}C{\sim}600^{\circ}C$ 사이에서는 완전연소가 이루어졌으며, 음식물 속의 미생물에 의한 분해로 인하여 pH는 4.26에서 7.6으로 증가하였다. 그리고 poly ester vinyl은 60일 동안의 운전에서 90% 이상의 분해가 이루어졌다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.32-35
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• 1999

Poly(arylene ether phosphin oxide) (PEPO), Udel$^{\circledR}$ P-1700, Ultem$^{\circledR}$ 1000. poly(hydroxy ether) (PHE), carboxy modified poly(hydroxy ether)(C-PHE) and poly(hydroxy ether ethanol amine) (PHEA) were utilized for a coating of carbon fibers. Interfacial shear strength(IFSS) of polymers to carbon fibers was also evaluated in order to understand the adhesion mechanism. IFSS was measured via micro-droplet tests, and failure surfaces were analyzed by SEM. Diffusion between polymer and vinyl ester resin was investigated as a function of styrene content; 33. 40 or 50wt.% and the solubility parameters of polymers were calculated. The results were correlated to the interfacial shear strength. The highly enhanced interfacial shear strength (IFSS) was obtained with PEPO coating, and marginally improved IFSS with PHE, Udel$^{\circledR}$ and C-PHE coatings, but no improvement with PHEA and Ultem$^{\circledR}$ coatings.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.143-146
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• 2002

Unsized AS-4 carbon fibers were etched by RF plasma and then coated via plasma polymerization in order to enhance adhesion to vinyl ester resin. The gases utilized for the plasma etching were Ar, $N_2 and O_2$, while the monomers used for the plasma polymerization coating were acetylene, butadiene and acrylonitrile. The conditions for the plasma etching and the plasma polymerization were optimized by measuring interfacial adhesion with vinyl ester resin via micro-droplet tests. Among the treatment conditions, the combination of Ar plasma etching and acetylene plasma polymerization provided greatly improved interfacial shear strength (IFSS) of 69MPa compared to 43MPa with as-received carbon fiber. Based on the SEM analysis of failure surface and load-displacement curve, it was assume that the failure might be occurred at the carbon fiber and plasma polymer coating. The plasma etched and plasma polymer coated carbon fibers were subjected to analysis with SEM, XPS, FT-IR or Alpha-Step, and dynamic contact angles and tensile strengths were also evaluated. Plasma polymer coatings did not change tensile strength and surface roughness of fibers, but decreased water contact angle except butadiene plasma polymer coating, possibly owing to the functional groups introduced, as evidenced by FT-IR and XPS.

• Composites Research
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• 제28권5호
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• pp.291-296
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• 2015

본 연구에서는 자동차 구조물의 경량화를 위해 자연섬유 복합재료를 적용하여 차량용 패널의 구조 설계 및 해석을 수행하였다. 구조 설계를 위해 Flax/vinyl ester 복합재료를 적용하였다. 섬유 복합재 패널의 제조공법은 VARTML(Vacuum Assisted Resin Transfer Molding-Light) 제조공법이 적용되었다. 구조 설계 후 충돌에 의한 구조물의 안전성을 분석하기 위해 충돌 실험을 수행하였다. 충돌 실험은 유럽 보행자 보호 기준에 맞게 수행하였으며 해석 결과를 검증하기 위하여 시편을 제작해 충격 실험을 수행하였다. 또한 충격 손상 후 구조물의 잔류강도를 측정하기 위해 손상을 가한 시편의 압축강도 실험을 수행하였다.

• Advances in nano research
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• 제13권1호
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• pp.97-111
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• 2022

In the present article, silica nanoparticles (SNPs) were exploited to improve the tribological and mechanical properties of vinyl ester/glass fiber composites. To the best of our knowledge, there hasn't been any prior study on the wear properties of glass fiber reinforced vinyl ester SiO₂ nanocomposites. The wear resistance is a critical concern in many industries which needs to be managed effectively to reduce high costs. To examine the influence of SNPs on the mechanical properties, seven different weight percentages of vinyl ester/nano-silica composites were initially fabricated. Afterward, based on the tensile testing results of the silica nanocomposites, four wt% of SNPs were selected to fabricate a ternary composite composed of vinyl ester/glass fiber/nano-silica using vacuum-assisted resin transfer molding. At the next stage, the tensile, three-point flexural, Charpy impact, and pin-on-disk wear tests were performed on the ternary composites. The fractured surfaces were analyzed by scanning electron microscopy (SEM) images after conducting previous tests. The most important and interesting result of this study was the development of a nanocomposite that exhibited a 52.2% decrease in the mean coefficient of friction (COF) by augmenting the SNPs, which is beneficial for the fabrication/repair of composite/steel energy pipelines as well as hydraulic and pneumatic pipe systems conveying abrasive materials. Moreover, the weight loss due to wearing the ternary composite containing one wt% of SNPs was significantly reduced by 70%. Such enhanced property of the fabricated nanocomposite may also be an important design factor for marine structures, bridges, and transportation of wind turbine blades.