• Textile Coloration and Finishing
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• 제29권1호
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• pp.37-44
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• 2017

An issue of major concern in the utilization of laminated composites based epoxy resin is associated with the occurrence of delaminations or interlaminar cracks, which may be related to manufacturing defects or are induced in service by low-velocity impacts. A strong interfacial filament/brittle epoxy resin bonding can, however, be combined with the high fracture toughness of weak interfacial bonding, when the filaments are arranged to have alternate sections of shear stress. To improve this drawback of the epoxy resin, UV-thermal dual curable resin were developed. This paper presents UV-thermal dual curable resin which were prepared using epoxy acrylate oligomer, photoinitiators, a thermal-curing agent and thermoset epoxy resin. The UV curing behaviors and characteristics of UV-thermal dual curable epoxy resin were investigated using Photo-DSC, DMA and FTIR-ATR spectroscopy. The mechanical properties of UV-thermal dual curable epoxy resin impregnated CF prepreg by UV curable resin content were measured with Tensile, Flextural, ILSS and Sharpy impact test. The obtained results showed that UV curable resin content improves the epoxy toughness.

• Journal of the korean academy of Pediatric Dentistry
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• 제31권3호
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• pp.534-540
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• 2004

Packable resins have been introduced in the market with high expectations as an alternative to amalgam. They are characterized by a high-filler load and a filler distribution that gives them a different consistency compared with the hybrid resins. The effect of high filler load on the microhardness and polymerization shrinkage of packable resins was tested. Hybrid resins were also tested to compared with the packable resins. As a result, packable resins showed a much greater microhardness value than hybrid resins. All the tested resins have a correlationship with the microhardness and filler content (vol%). The packable resins showed much less polymerization shrinkage than hybrid resins. The filler content and polymerization shrinkage were inversely correlated in the tested resins.

• Polymer(Korea)
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• 제24권4호
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• pp.513-519
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• 2000

The effect of petroleum resin as a tackifier for polyalphaolefin (APAO) hot melt adhesive on thermal properties, crystallinity and adhesion strength was investigated. The presence of petroleum resin resulted in the melting temperature decrease in APAO/petroleum blend, especially, in APAO with low ethylene content/C$_{5}$ petroleum blend. It was also found that petroleum resin caused the decrease of crystallinity regardless of ethylene content in APAO. The maximum adhesion strength was found to be at 50/50 (APAO/petroleum) composition. $C_{5}$ resin was more effective to increase adhesion strength than $C_{9}$ for APAO with high ethylene content. In addition, it was found that the adhesion strength was improved with the decrease of crystallinity in APAO/petroleum resin hot melts.

• Textile Coloration and Finishing
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• 제33권2호
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• pp.79-86
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• 2021

This study investigated the effect of a pigment (C. I. Pigment Red 122) addition on mechanical properties of the epoxy resin, diglycidyl ether of bisphenol F (DGEBF) and G640 curing agent. The K/S value, thermal properties, tensile properties, and fracture toughness of the prepared epoxy samples were evaluated. When the pigment was added to the DGEBF/G640 epoxy system, the color of the epoxy resin changed to red from transparent and yellowish color, and the K/S value in the red region increased as the pigment content increased. When the pigment content was increased up to 0.1 phr, the tensile strength was improved up to 21.8 %, whereas the pigment content was over 0.1 phr, the tensile strength decreased. The fracture toughness was improves up to 23.1 % until the amount of pigment added was up to 0.2 phr, and then decreased when the amount of the pigment added was more than 0.2 phr. This attributed to the aggregation of the pigments in the epoxy resin when the amount of the pigment added was more than 0.2 phr. Therefore, the coloration of the epoxy resin with an organic pigment must be carried out very carefully because the coloration of epoxy resin affects its mechanical properties.

• Proceedings of the KSME Conference
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.246-250
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• 2001

In resin transfer molding (RTM), resin is forced to flow through the fiber perform of inhomogeneous permeability. This inhomogeneity is responsible for the mismatch of resin velocity within and between the fiber tows. The capillary pressure of the fiber tows exacerbates the spatial variation of the resin velocity. The resulting microscopic perturbations of resin velocity at the flow front allow numerous air voids to form. In this study, a mathematical model was developed to predict the formation and migration of micro-voids during resin transfer molding. A transport equation was employed to account for the migration of voids between fiber tows. Incorporating the proposed model into a resin flow simulator, the volumetric content of micro-voids in the preform could be obtained during the simulation of resin impregnation.

• Journal of Pharmaceutical Investigation
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• 제18권2호
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• pp.83-88
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• 1988

We examined effects of crosslinking agents, i.e., ethyleneglycol dimethacrylate (EGD) and butanediol dimethacrylate (BDD) containing ester groups on chloromethylation of crosslinked polystyrene resin matrices. It was proved that the ester group in methylmethacrylate (MMA) accelerates the chloromethylation of the divinylbenzene (DVB)-crosslinked styrene-MMA copolymer. As the MMA content increased in the styrene-MMA copolymers, the chloromethylation was enhanced. Complete chloromethylation was obtained at about 25% MMA content.

• Tribology and Lubricants
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• 제16권4호
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• pp.266-273
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• 2000

The friction characteristics of phenolic resin and model friction materials were investigated with the content of hexamethylenetetamine (HEXA). At 10 wt.% of HEXA, the phenolic resin and model friction materials showed the most stable friction coeffcient in constant temperature test at various test conditions because of its good thermal stability and proper curing reaction. It was found from constant interval test in mild condition that the friction coeffcients of friction materials cured with 10 wt.% of HEXA was the highest and stable values in the whole range of braking operations. However, at the severe condition in constant interval test, the friction coefficient of friction materials cured with 10 wt.% to of HEXA was lowered and as the number of braking operation increased, the values became stable. In order to obtain the thormal stable friction materials, the content of HEXA from 5 to 10 wt.% could be recommended.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.114-114
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• 2001

The thermal and friction characteristics of phenolic resin and model friction materials were investigated with the content of acrylonitrilebutadienerubber(NBR). The thermal characteristics of material was performed by dynamic mechanical thermal analysis and differential scanning calorimetry. The friction and wear characteristics of the material were determined by using friction material testing machine. The results show that with the more content of rubber, the loss modulus of friction material was increased. The friction coefficient and the specific wear rate with various NBR contents were reported.

• Journal of Korean Society of Forest Science
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• 제30권1호
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• pp.19-29
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• 1976

The fiberboard and paper mills in this country are much affected by the price hikes and shortage of phenolic resins, since phenolic acid as a raw material depends on imported good. It is prerequisite to fiberboard industry to help replace with other sized and stabilize the prices and supply of them, improving the quality of boards. Thus, the present study was carried out to examine the effect of strength increasing sized such as urea formaldehyde resin (anion and cation type) and urea melamine copolymer resin, on the quality of the wet forming hardboard, and comparing them with two types of proprietary modified melamine resins, and ordinary size, phenol resin. The Asplund pulp was prepared from wood wastes mixed with 20 percent of lauan and 80 percent of pines as a fibrous material. After sizing agents were added at a pH of 4.5 for 10 minutes with alum in the beater, the stock was made in the form of wet sheet, prepared, and then performed by hot pressing cycle: $180^{\circ}C$, $50-6-5kg/cm^2$, 1-2-7 minutes. The properties of hardboard were examined after air conditioning. The results obtained are summarized as follows: 1. There is a significant difference in specific gravity among hardboards that were treated with strength increasing resins, but no difference is effected by the increase in the resin content. In the case of modified melamine resin, its specific gravity is highest. The middle group comprises cation type of urea resin, anion type of urea resin, and acid colloid of urea-melamine copolymer resin. The lowest is phenolic resin. 2. The difference of the moisture content of hardboard both by the resins and by the amount of each resin applied is significant. The moisture content of hardboard becomes lower along with the increase of each resin content, but there is no difference between 2 and 3 percent. 3. For water absorption, there is a significant difference both in the adhesives used and in the amount of paraffin wax emulsion. The water resistance becomes higher inn proportion to the content of the paraffin wax emulsion. To satisfy KS F standards of the water resistance, a proprietary modified melamine resin (p-6100) and modified cation type of urea resin (p-1500) do not require any paraffin wax emulsion, but in the case of anion type of urea resin, cation type of urea resin, and urea-melamine copolymer resin, 1 percent of paraffin wax emulsion is needed, and 2 percent of paraffin wax emulsion in the case of phenolic resin. 4. The difference of flexural strength of hardboard both by the resins and by the amount of each resin is significant. Modified melamine resin shows the highest degree of flexural strength. Among the middle group are urea-melamine copolymer resin, p-1500, anion type of urea resin, and cation type of urea resin. Phenolic resin is the lowest. The cause may be attributable to factors combined with the pressing temperature, sizing effect, and thermal efficiency of press platens heated electrically. 5. Considering the economic advantages and properties of hardboard, it is proposed that urea-melamine copolymer resin and cation type of urea resin be used for the development of the fiberboard industry. It is desirable to further develop the modified urea-melamine copolymer resin and cation type of urea resin through continuous study.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제14권2호
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• pp.87-92
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• 2015

The injection molding process is widely used in the production of most plastic products. In order to make metal-colored plastic products like those found in modern luxury home alliances, metallic pigments are mixed with a basic resin material for injection molding. However, process control for metal-colored plastic products is extremely difficult due to the non-uniform melt flow of the metallic resin pigments. In this study, the effect of process parameters on the quality of a metal-colored plastic product is evaluated. A rapid mold cooling method using a compressed cryogenic fluid is also proposed to decrease the content of undesired compounds within the plastic product.