• 대한기계학회논문집
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• 제16권2호
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• pp.200-206
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• 1992

The effect of fiber diameter and gauge length on pull-out test for the interfacial properties in fiber reinforced resin composites have been investigated and these results have been arranged as statistical analysis. The fiber and matrix resins used for this study were stainless steel fiber (SUS316) and carbon fiber (high strength type), epoxy and high density polyethylene resin. From this study, it has been found that shear strength are constant regardless of gauge length of pull-out test and coefficient of variation depend on fiber diameter. In addition, it has been found that the interfacial shear strength decreased with the increasing fiber diameter, and in all case, Weibull parameter (m) has approximately 1.2/C.O.V.

• Fibers and Polymers
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• 제2권1호
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• pp.135-139
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• 2001

Poly(hydroxamic acid) resin beads were prepared and complexed with various metal ions. We used IR spectroscopy to investigate the structure of metal complex. It proved that the products formed by introduction of metal ions gave stable and colored complex. It was found that the resin bead as synthesized would be a good column packing material for continuous extraction. Energy dispersive spectroscopy was use to study the distribution of metal ions in the resin matrix. It could be tentatively concluded that adsorption and diffusion of metal ions in the chelating resins mainly depended on the loading of the resin matrix which indicated interacting sites with metal ions.

• 공업화학
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• 제16권1호
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• pp.117-122
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• 2005

가시광선 중합형의 치아수복용 고분자 복합체(polymeric dental restorative composites, PDRC)에 있어서 여러 종류의 3급 아민계 광증감제가 PDRC의 치과적 물성에 미치는 영향을 기계적 물성과 심미적 특성을 분석한 후 고찰하였다. PDRC 제조에 사용한 barium silicate 필러는 아크릴계 resin matrix와의 혼화성 증가를 위해 표면을 소수성으로 처리하여 사용하였다. 광중합에 필요한 광개시제로는 resin matrix를 기준으로 camphorquinone을 0.5 wt%로 하여 사용하였다. 그 결과, 제조된 PDRC의 기계적 물성과 심미적 특성은 사용한 광증감제의 함량보다는 화학적 구조에의 의존성이 더 큼을 알 수 있었다.

• 공업화학
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• 제1권2호
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• pp.116-123
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• 1990

감광성 orthonaphthoquinonediazide-sulfonyl 유도체를 합성하고, 그 감광특성에 대해 검토한 결과, UV에 의해 광변환 되어, 알칼리 가용성의 분해화합물이 생성됨을 확인하였다. 이 유도체를 PAC로, m-cresol novolac을 matrix resin으로 photoresist를 제조하고 감광 특성을 고찰하여, 미세 패턴용 photoresist로의 타당성을 확인하였다. 3, 4, 5-Trihydroxybenzophenone 의 벌키한 공명 구조는 노광부의 감도와 가용성을 향상시켰으며, PAC 와 matrix resin의 혼합 무게비가 3:8 일 때 가장 적절한 dissolution rate를 나타냈으므로, 이 photoresist가 정해진 조건 하에서 감도, 해상력이 가장 우수하였다.

• 폴리머
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• 제33권2호
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• pp.153-157
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• 2009

치과용 복합 재료의 레진 기질은 주로 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane(Bis-GMA)와 이의 점도 감소를 위한 희석제인 triethylene glycol dimethacrylate (TEGDMA)로 구성되어 있다. TEGDMA는 복합 재료의 중합 수축률과 흡수율을 증가시켜 치과용 복합 재료의 사용에 제약 요소로 작용하고 있다. 본 연구에서는 희석제 첨가량을 감소시켜 희석제 첨가에 따른 문제점을 해결하기 위해 diethylene glycol dimethacrylate(DEGDMA)와 ethylene glycol dimethacrylate(EGDMA)를 대체 희석제로 검토하였다. 이들 희석제를 이용하여 치과용 복합 재료를 제조해 특성 변화를 관찰한 결과 기존 소재에 비해 중합 수축를 감소와 기계적 물성의 증가가 관찰되었다. 특히 DEGDMA 혹은 EGDMA를 사용한 경우 평형 흡수율이 감소되어 흡수에 따른 물성 저하가 기존 재료에 비해 감소하였다.

• Journal of Pharmaceutical Investigation
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• 제18권2호
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• pp.69-81
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• 1988

We studied on the synthesis of chloromethylated polystyrene as a precursor of optically active polymers for direct resolution of optical isomers. Changing the degree of crosslinking and the kind of crosslinking agents, several polystyrene resin matrices were synthesized. The matrices were chloromethylated with methylal and chlorosulfonic acid as chloromethylating agents. The effects of solvents of various dielectric constants on the chloromethylation were quantitavely examined. We also synthesized chloromethylated polystyrene of macroreticular type that retained large surface area and good physical stability. The differences between the macroreticular type and macroporous type were investigated.

• 대한소아치과학회지
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• 제50권4호
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• pp.396-408
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• 2023

이 연구의 목적은 유구치를 재현한 인공치를 대상으로 인접면 복합레진 수복 시 매트릭스 시스템에 따른 인접면의 외형, 접촉면의 크기 및 수복 전과 후의 부피 차이를 비교해 보는 것이다. 네 가지 종류의 인공치에 Circumferential 매트릭스 시스템에 해당하는 Tofflemire Matrix System과 Sectional 매트릭스 시스템에 해당하는 Palodent V3 Sectional Matrix System, myJunior Kit를 이용하여 복합레진을 수복하고 3D 모델링 과정을 거쳐 분석되었다. Sectional 매트릭스 시스템을 사용한 경우에서 오목한 인접면 외형이 형성될 확률이 높았으며 더 큰 접촉 면적과 부피가 형성되었다. 이는 Sectional 매트릭스 시스템에 사용되는 매트릭스 밴드의 완전 연질(Dead soft) 특성에 의한 변형으로 인해 접촉점 주변으로 과량의 레진이 적용될 수 있기 때문이다. 게다가 Sectional 매트릭스 시스템에 포함된 고무 웨지가 매트릭스 밴드를 와동에 잘 적합 시키지 못할 가능성이 있다. 따라서 이번 연구의 결과를 바탕으로 유구치 인접면을 Sectional 매트릭스 시스템을 이용해 복합레진 수복하는 경우, 형태학적 관점을 고려한 신중한 사용이 요구된다.

• Restorative Dentistry and Endodontics
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• 제27권1호
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• pp.77-86
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• 2002

Current composites are made with dimethacrylate monomers and silane-treated silica microfillers, either alone or with silane treated glass fillers The main reasons for clinical failure of dental composites are secondary caries, wear and fracture. Most of practitioner want to get a composite which is more tougher under occlusal stress, less polymerization contraction, and better handling properties in application clinically. The aim of this study was to investigate the influence of resin matrix with various flows on the physical proper-ties such as fracture toughness and degree of conversion of the experimental resins. It was hypothesized that flexible or tough resin composites can be designed by judicious choice of monomer composition Various flow resin matrices containing Bis-GMA, UDMA, and TEG-DMA were made by altering the pro-portion of the monomers. After the unfilled resins were light-cured for different light intensity, the fracture toughness(K$_{1c}$) was measured according to ASTM standard using the single edge notched geometry, and degree of conversion(DC) was measured by FTIR. And experimental composites were formulated with variations in the proportion of silanated quartz and strontium glass fillers as 60, 75, and 77wt%. Also, the physical properties of composites with various filer contents were evaluated as same manner. All resulting data were compared by ANOVA/Tukeys test at 0.05 level. The results were as follows; 1. The degree of conversion of high flow resin containing less Bis-GMA was higher than that of low flow unfilled resin 2. While the degree of conversion of unfilled resin was increased according to light intensity for polymerization, there was no significant increase with moderate and high light intensity. Also, the fracture toughness was not increased by high light intensity. 3. The fracture toughness was high in the low flow unfilled resin containing higher contents of Bis-GMA. 4. There was a significant increase for fracture toughness and a tendency for degree of conversion to be reduced when the content of fillers was increased. 5. In the experimental composites, the flow of resin matrix did not affected on the fracture toughness, even, which was decreased as increase of viscosity. These results showed that the physical properties of a dental composite could be attributed to the flow of resin matrix with relative content of monomers. Specific combination of resin monomers should be designed to fulfil the needs of specific indication for use.

• Carbon letters
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• 제5권4호
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• pp.159-163
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• 2004

The polymer-ceramic hybrid, known as 'ceramer', was synthesized by a sol-gel process by incorporating different amount of alkoxide as source of silicon in resorcinol-formaldehyde in presence of basic catalyst to get different percentage of silicon in ultimate carbonized composites. FTIR of the ceramer confirms that it is a network of Si-O-Si, Si-O-$CH_2$ and Si-OH type groups linked with benzene ring. Different amount of silicon in the ceramer exhibits varying temperature of thermal stability and lower coefficient of thermal expansion as compared to pure resorcinol-formaldehyde resin. The lower value of CTE in ceramer is due to existence of silica and resorcinol -formaldehyde in co-continuous phase. Unidirectional composites prepared with ceramer matrix and high-strength carbon fibers show lower value of flexural strength at polymer stage as compared to those prepared with resorcinol-formaldehyde resin. However, after heat treatment to $1450^{\circ}C$, the ceramer matrix composites show large improvement in the mechanical properties, i.e. with 7% silicon in the ceramer, the flexural strength is enhanced by 100% and flexural modulus value by 40% as compared to that of pure resorcinol-formaldehyde resin matrix composites.

• Advanced Composite Materials
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• 제17권4호
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• pp.333-341
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• 2008

A novel manufacturing method for hybrid composites filled with carbon nanotubes (CNTs) and aramid fibers is proposed. To disperse the CNTs in the epoxy matrix with the presence of aramid fibers, CNT/polyethyleneoxide (PEO) composites are prepared and utilized because PEO is miscible in the epoxy resin. After thin films are made of the CNT/PEO composite and placed together with the aramid fibers, the epoxy resin is infused to them. The PEO is dissolved in the epoxy and then the CNTs are dispersed in the PEO/epoxy matrix between aramid fibers before the pre-heated matrix is cured. It is found that the PEO is completely miscible with the epoxy resin and CNTs are dispersed well in the space between the aramid fibers.