• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.536-538
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• 2011

In this study, the moisture absorption behaviors of the CNT reinforced unsaturated polyester composites were investigated along with exposure temperature and time. The tensile properties of the specimens were evaluated to identify the effect of absorbed moisture on the mechanical properties. The exposure temperatures of $25^{\circ}C$ and $75^{\circ}C$ were considered and the exposure time up to 600 hours was applied. According to the results, moisture absorption rate was increased as CNT content and exposure temperature were increased. The rate of decrease in tensile strength of the CNT reinforced unsaturated polyester composites was reduced due to the reinforcing effect of CNT compared to the unsaturated polyester resin.

• Polymer(Korea)
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• v.25 no.6
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• pp.774-781
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• 2001

In order to reuse the waste matters, the polyester hybrid composites were fabricated with the waste stone (WSP) and waste tire (WTC). Before mixing, the waste fillers were treated with the silane coupling agent [${\gamma}$-methacryloxy propyl trimethoxy silane(${\gamma}$-MPS)] for enhancing the dispersion of the fillers and interfacial bonding with polymer matrix. Mechanical properties and morphologies of the resulted hybrid composites were investigated with the filler content. The hybrid composites containing surface treated fillers have high initial thermal decomposition temperature and low weight loss compared to the untreated one. The highest mechanical properties of composites were obtained with the ${\gamma}$-MPS (2 wt%) treated fillers. The porosity of composite increased with the content of organic filler which can be reduced by the silane surface treatment of fillers. The pore size distribution of the composites varied with the waste filler content.

• Clean Technology
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• v.16 no.4
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• pp.245-253
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• 2010

Optimum conditions for UV-radiated photopolymerization of unsaturated polyester that could be used as protecting layer of large diameter pipe were investigated in this paper. UV photopolymerization method was selected to solve the problems, arising when thermal polymerization by organic peroxide was used, such as the instability of peroxide initiator, the evolution of volatile organic compound, and thermal deformation of product. Two of the photo-initiators (Irgacure 819 and Darocure 1173) well known for its penetrating ability deep into the polymer layer were selected, and the optimum conditions for photopolymerization (1.5 phr initiator content, 1:1.2 initiator ratio, Ga lamp for UV source) were found from the thermal and mechanical test results of the resultant UP polymers. In addition, composite materials containing UP polymer and glass fiber were tested for hardness, impact strength, and flexural strength to find that the impact strength of composite significantly improved.

• Composites Research
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• v.35 no.4
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• pp.255-260
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• 2022

Lightweight hydrant tanks increase the amount of water that can be carried by fire trucks, resulting in longer water spray times during the initial firefighting process, which can minimize human and property damages. In this study, the applicability of carbon-fiber-reinforced polymer (CFRP) composites as a material for lightweight hydrant tanks was investigated. In particular, the resin for manufacturing CFRP hydrant tanks must meet various requirements, such as excellent mechanical properties, formability, and dimensional stability. In order to identify a resin that satisfies these conditions, five commercially available resins, including epoxy(KFR-120V), unsaturated polyesters(G-650, HG-3689BT, LSP8020), vinyl ester(KRF-1031) were selected as candidates, and their characteristics were analyzed to investigate the suitability for manufacturing a CFRP hydrant tank. Based on the analyses, KRF-1031 exhibited the most suitable properties for hydrant tanks. Particularly, CFRP with KRF-1031 exhibited successful results for thermal stability and elution tests.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.9-20
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• 2005

This study was carried out to select most efficient bonding methods of geogrid at the interface of old concrete pavement before placing asphalt overlay layer for reflection cracking retardation. Three bonding methods, a RSC-4 emulsified asphalt, a compound and an unsaturated polyester resin (UPR) were compared in this study. Three types of asphalt mixture (AC 60-80, RLDPE 8%, PG 76-22) and a dense-graded aggregate were used for overlay asphalt pavement. A reinforcing material which consists of a woven fabric underneath a glass fiber grid was used. An expedite test method which is for simulating mixed mode (mode I and II) fracture test was performed using a wheel tracker in laboratory. Cracking development by load repetition was measured as fatigue life (number of load cycle) and expansion of specimen body were measured for each test specimen. The results showed that UPR was the best and RSC-4 the next. But considering field applicability, RSC-4 was considered as an appropriate choice for bonding reinforcing material.

• Journal of Adhesion and Interface
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• v.22 no.2
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• pp.63-68
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• 2021

Unsaturated Polyester Resin (UPR) is in general used as a resin to prepare for composite materials with reinforcing materials such as glass fibers. UPR, a thermosetting resin, is used in industry to prepare for sheet molding compound (SMC) molding prepreg that has excellent productivity and is advantageous for mass production among various molding methods of composite materials. The fiber-reinforced composite material using UPR as a matrix material is light and has the advantage of excellent physical properties, but it is weak against impact and is fragile. Four types of polyurethane were synthesized and added to UPR resin to overcome the shortcomings.