• 환경위생공학
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• 제11권1호
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• pp.17-25
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• 1996

Resins with cryptand 22 macrocyclic ligand attached to chloromethylated styrene-1,4-divinylbenzene by substitution reaction were prepared and the effect of pH, metal concentration and cross-linkage of the matrix on the adsorption for $UO_2^{2+}$, $Cd^{2+}$ and $Sm^{3+}$ was investigated. The metal ion was not adsorbed on the resins pH range below 3 but above pH 4 fast adsorption behavior was showed. The resin selectivity determined in ethanol matrix was in increasing order $UO_2^{2+}{\;}>Cd^{2+}{\;}Sm^{3+}$. In addition, these metal ion could be separated on the column packed with 1% crosslinked resin by pH 2.5 $HNO_3$ as an eluent.

• 대한치과의사협회지
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• 제24권7호통권206호
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• pp.633-642
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• 1986

In order to evaluate the effects of various finishing devices (Sof-Lex disc, diamond point, rubber point, fussure bur) on the surface roughness or two composite resins (Restodent, Enamelite 500), 15 specimens for each composite resin were made in the mold. Composite resin was prepared on the mixing pad by manufacturer's direction and filled in the mold cavity. A sheet of matrix is immediately placed on it and hold for 5 minutes to polymerize the resin. Surface finish was done after 10 minutes from the start of mixing. Scanning electron microscopy and surface profilometer were used to evaluate the surface roughness, porositites and striations of dental composite resins. The following results were observed; 1. The best finished surface was formed by celluloid matrix band. 2. Rubber point was excellent polishing device for Restodent. 3. Sof-Lex disc was the device of choice for polishing Enamelite 500. 4. Different polishing methods were effective for different composite resins. 5. SEMs of variously finished surfaces supported the profilometer measurements.

• Carbon letters
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• 제1권1호
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• pp.1-5
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• 2000

The effect of surface free energy on the positive temperature coefficient (PTC) of carbon black/thermoplastic resin composites was investigated. The thermoplastic resins such as EVA, LDPE, LLDPE and HDPE were used with the addition of 30 wt.% of the carbon black. The surface free energy of the composites was studied in the context of two-liquid contact angle measurements, i.e., deionized water and diiodomethane. It was observed that the resistivity on PTC composites Was greatly increased near the crystalline melting temperature, due to the thermal expansion of polymeric matrix. From the experimental results, it was proposed that the decrease of surface free energy induced by interactions between carbon black surfaces and polymer chains is an important factor to the fabrication of a PTC composite made of carbon black and polymeric matrix.

• 한국정밀공학회지
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• 제21권2호
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• pp.210-217
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• 2004

In this study, a new process, named as nano replication printing(nRP) process, is developed for printing any figure in the range of several micrometers by using voxel matrix scanning scheme. In this newly developed process, a femto-second laser is scanned on a photosensitive monomer resin in order to induce polymerization of the liquid resin according to a voxel matrix which is transformed from bitmap format file. After the polymerization, a droplet of ethanol is dropt to remove the unnecessary remaining liquid resin and then the polymerized figures with nano-scaled precision are only remaining on the glass plate. By the nRP process, any figure file of bitmap format could be reproduced as nano-scaled precision replication in the range of several micrometers. Also, nano/micro-scaled patterns for an extremely wide range of applications would become a technologically feasible reality. Some of figures with nano-scaled precision were printed in scaled replication as examples to prove the usefulness of this study.

• 공업화학
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• 제2권4호
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• pp.301-310
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• 1991

대표적인 열가소성 수지인 에폭시 수지는 그 용도 및 응용분야가 광범위하지만, 경화 후 수지의 brittleness와 고온 및 습윤하에서 물성이 좋지 않아 시용에 제한을 받고 있다. 본고에서는 수지의 최대결점인 brittleness 개선과 고온 습윤 특성의 향상 방법에 대해 고찰하였다. Brittleness 개선 방법으로는 rubber 및 열가소성 수지를 에폭시 수지에 도입하여, 이에 따른 toughness 향상 정도를 중점적으로 다루었으며, 고온 습윤 특성을 향상시키기 위해 에폭시 수지의 molecular design 및 열가소성 수지의 응용방법에 대해 기술하였다.

• Transactions on Electrical and Electronic Materials
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• 제14권2호
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• pp.53-58
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• 2013

Graphene-based polymer nanocomposites are very promising candidates for new high-performance materials that offer improved mechanical, barrier, thermal and electrical properties. Herein, an approach is presented to improve the mechanical, thermal and electrical properties of unsaturated polyester resin (UPR) by using graphene nano sheets (GNS). The extent of dispersion of GNS into the polymer matrix was also observed by using the scanning electron microscopy (SEM) which indicated homogeneous dispersion of GNS through the UPR matrix and strong interfacial adhesion between the GNS and UPR matrix were achieved in the UPR composite, which enhanced the mechanical properties. The tensile strength of the nanocomposites improved at a tune of 52% at a GNS concentration of 0.05%. Again the flexural strength also increased around 92% at a GNS concentration of 0.05%. Similarly the thermal properties and the electrical properties for the nanocomposites were also improved as evidenced from the differential scanning caloriemetry (DSC) and dielectric strength measurement.

• 접착 및 계면
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• 제15권2호
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• pp.49-56
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• 2014

본 연구에서는 아연 코팅 스틸코드와 접착증진제가 적용된 배합고무와의 접착 특성을 연구하였다. 접착증진제로는 cobalt boroacylate (코발트 염), resorcinol-formaldehyde resin (RF resin) 그리고 hexamethoxymethylmelamine (HMMM)을 사용하였다. 코발트 염이 첨가된 배합고무에서는 코발트 염이 아연 코팅 스틸코드 표면에서 아연 황화물 성장을 촉진시켜 코발트 염이 포함되지 않은 배합고에 비하여 pullout force가 증가하는 것을 확인하였다. 또한 코발트 염, RF resin과 HMMM을 모두 적용한 배합고무의 경우, 코발트 염은 아연 황화물 성장을 촉진시키고, RF resin과 HMMM은 배합고무의 modulus를 높여 고무 matrix로 성장한 아연 황화물을 더 강하게 interlocking하기 때문에 pullout force와 스틸코드의 고무 부착율이 가장 높게 나타난다는 것을 확인하였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.76-81
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• 1997

In the past polyester was usually used as the matrix of all fiber-reinforced plastic (FRP). Nowadays, however, epoxy resin has taken the place of polyester due to its superior properties. If the cutting properties of epoxy resin are unknown, It is difficult to find the optimum cutting conditions of all fiber-reinforced plastic such as CFRP. AFRP. GFRP. In this paper, I will study the cutting properties of epoxy resin by testing surface roughness.

• 반도체디스플레이기술학회지
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• 제12권1호
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• pp.23-28
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• 2013

Epoxy resins are widely used in microelectronics packaging such as printed circuit board and encapsulating for semiconductor manufacturing. Water can diffuse into and through the epoxy matrix systems and moisture absorption at boarding interfaces of matrix resin systems can lead to a hydrolysis at the interfaces resulting in delamination of encapsulating materials. In the study, the changes of diffusion coefficient and moisture content ratio of epoxy resin systems with nano-sized fillers according to the change of liquid type epoxy resins were investigated. RE-304S, RE-310S, RE-810NM and HP-4032D as a epoxy resin, Kayahard AA as a hardener, and 1B2MI as a catalyst were used in these epoxy resin systems. After curing, moisture content ratios were measured with time under the 85 and 85% relative humidity condition using a thermo-hydrostat. The maximum moisture absorption ratio and diffusion coefficient of EMC decrease with the filler content. It can be seen that these decreases are due to the increase of filler surface area and the decrease of moisture through channel with the content of nano-sized filler.

• 폴리머
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• 제38권6호
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• pp.726-734
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• 2014

Three different types of additives, thiokol, epoxidized natural rubber (ENR) and epoxidized linseed oil (ELO), were dispersed in an epoxy matrix before being used in glass fiber (GF) composites, and their effects on the mechanical and dielectric properties of epoxy resin and glass fiber reinforced epoxy composites (GF/EP) were examined. The addition of each of 7 phr ENR, 9 phr ELO and 5 phr thiokol into the epoxy resin increased the fracture toughness significantly by 56.9, 43.1, and 80.0%, respectively, compared to the unmodified resin. The mode I interlaminar fracture toughness of the GF/EP at propagation was also improved by 26.9, 18.3 and 32.7% when each of 7 phr ENR, 9 phr ELO, and 5 phr thiokol, respectively, was dispersed in the epoxy matrix. Scanning electron microscopy showed that the additives reduced crack growth in the GF/EP, whereas their dielectric measurements showed that all these additives had no additional effect on the real permittivity and loss factor of the GF/EP.