• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.2
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• pp.107-115
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• 1997

The ultraviolet(UV)-curable materials are widely used in inks and coatings. In this paper is designed to develop materials having flexibility and functionality with UV-curable acrylate monomer and alkyd resin. At first, phase diagram is prepared for miscibility of UV -curable acrylate monomer with alkyd resin. Also the gel fraction and dynamic viscosity are measured to curing speed of mixing system. In results, it has been demonstrated that miscibility and curing speed are greatly influenced by alkyd resin content.

• Composites Research
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• v.37 no.3
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• pp.215-218
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• 2024

Liquid crystalline thermosetting epoxy oligomer DD-A was synthesized with Diglycidyl ether of 4,4'-dihydroxy-α-methylstilbene (DGE-DHMS) and aniline in a ratio of 2:1 and cured with a catalytic curing agent, 1-Methyl Imidazole. The gelation times and vitrification times were measured to create Time-Temperature-Transition Diagrams with liquid crystalline phase changes. It was found that the gelation and vitrification times were decreased as the concentration of curing agent increased, and the vitrification curve showing a typical S-shape was confirmed.

• Macromolecular Research
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• v.12 no.1
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• pp.11-21
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• 2004

Toughening of epoxy resins for improvement of crack resistance has been the subject of intense research interest during the last two decades. Epoxy resins are successfully toughened by blending with a suitable liquid rubber, which initially remains miscible with epoxy and undergoes a phase separation in the course of curing that leads to the formation of a two-phase microstructure, or by directly blending preformed rubbery particle. Unlike the situation for thermoplastics, physical blending is not successful for toughening epoxy resins. Recent advances in the development of various functionalized liquid rubber-based toughening agents and core-shell particles are discussed critically in this review.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.8-12
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• 1976

The major subjects of this experiment are to evaluate the mechanical properties of the curing gum for prevention of vibration and to study for related problems. In the prevention of vibration by the curing gum, the results are as follows. When the value of forced frequency over natural frequency is less than $\sqrt{2}$, it may well be used that the value$(1\%-2\%,\;4\%-5\%)$ of damping coefficient over critical damping coefficient of the curing gum is large. When the value of forced frequency over natural frequency is larger than $\sqrt{2}$, it may well be used that the value $(2.5\%-3.5\%)$ of the curing gum is low. If the larger value of logarithmic decrement may be used, the low curing gum is preferred. The conductive range of sulphur contents of the curing gum is $3.3\%-3.5\%$ in the light of phase angle, resilience, and damping coefficient over critical damping coefficient.

• Journal of Adhesion and Interface
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• v.7 no.4
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• pp.32-38
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• 2006

A series of organic-inorganic hybrids, PCL/EP/$SiO_2$, involving epoxy resin and triethoxysilane-terminated polycaprolactone elastomer (PCL-TESi) were prepared via polymerization of diglycidyl ether of bisphenol A (DGEBA) with amine curing agent KB-2 and sol-gel process of PCL-TESi. The curing reactions were started from the initially homogeneous mixture of DGEBA, KB-2 and the PCL-TESi. The organicinorganic hybrids containing up to 4.95% (wt) of $SiO_2$ were obtained and characterized by FT-IR, transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). It was experimentally shown that the swelling property in toluene, morphologies and thermal properties of the resulting hybrids were quite dependent on the contents of $SiO_2$. The crosslink network density decreases with increasing of the PCL-TESi. And in TEM, the phase separated morphology of these hybrids was found, which resulted from the coagulation of Si-O-Si networks resulting from $-Si(OC_2H_5)_3$ of PCL-TESi self-curing by hydrolytic silanol condensation, with the advancement of the curing reaction in the modified epoxy resin systems. Meanwhile, the change of the $SiO_2$ content made the morphologies changed from aggregated particles of Si-O-Si in the hybrid to nanocluster of interconnected Si-O-Si particles, then to aggregated Si-O-Si dispersing in the continuous cured epoxy phase again, and last to co-continuous interpenetrating network. The glass transition behavior of the hybrid material was cooperative motion of large chain segments, which were hindered by the inorganic Si-O-Si network. And in TG analysis, the characteristic temperature at 5% of weight loss was evidently increased from $120.5^{\circ}C$ of pure cured epoxy to $277.6^{\circ}C$ of 3.84% (wt) of $SiO_2$ modified epoxy due to the existence of Si-O-Si when PCL-TESi was added in the hybrid.

• Journal of the Korean Ceramic Society
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• v.31 no.2
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• pp.194-200
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• 1994

Pitchstone(Volcanic ejecta) reacts with CaO in hot water and increases its sedimentary volume by forming Ca(OH)2 and calcium silicate hydrates. ALC was prepared from the various gelling and curing conditions using the ratio of pitchstone/CaO was 2(CaO/SiO2 mol ratio=0.81), and then the products, crystalline phases and physical properties of ALC with experimental conditions was investigated. The crystalline phase of tobermorite with laths and plate type and the porosity were increased, the thermal conductivity was decreased with increasing gelling temperature and time. But modulus of rupture has maximum value when gelling time was 2 hrs. Othwrwise the bulk density nearly unchanged with increasing curing temperature, but the modulus of rupture was increased.

• Journal of the Korea Institute of Building Construction
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• v.21 no.2
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• pp.97-104
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• 2021

This study aims to develop non-sintered cement that can replace the Portland cement by utilizing industrial by-products. As a suggestion, the physical properties of non-sintered cement mortar depending on the curing method were investigated with ground granulated blast furnace slag, class C fly ash, and class F fly ash. As a result of the study, it was found that the strength performance and absorption rate were improved through the heat treatment process after steam curing. It was confirmed through crystal phase analysis that the hydration was accelerated after heat treatment, and the bonding material formed a dense internal structure.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.19-29
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• 2002

The purpose of this study was to compare the polymerization shrinkage and the compressive strength of composite and compomer cured with two different light sources ; conventional halogen-light curing unit and recently-developed plasma arc curing unit. The 'strain gauge method' was used for determination of polymerization shrinkage and the compressive strength was measured by universal testing machine. The results of the present study can be summarized as follows: 1. Filling materials in polyethylene molds showed the initial expansion in the early phase of polymerization. This was followed by the rapid contraction in volume during the first 60 seconds and gradually diminished as curing process continued. 2. The polymerization shrinkage in tooth samples was generally lower than in the mold samples. 3. The generally lower amount of linear polymerization shrinkage was observed in compomer and plasma arc curing unit group when compared to composite and conventional curing unit. 4. The higher compressive strength values was found in composite groups regardless curing methods. The results of this study strongly support the application of plasma arc system and fluoride-containing compomer in the field of clinical pediatric dentistry claiming its effectiveness in curing the esthetic dental materials and the anticariogenic capacity.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.163-166
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• 2002

For the development of an all composite unmanned aerial vehicle (UAV), manufacturing consideration in design phase, works for composite parts fabrication, subassembly and final assembly are summarized. In design phase, to maximize the advantage of composite material, manufacturing processes such as cocuring, cobonding and secondary bonding are introduced. For the curing of designed parts, composite tools are designed and manufactured. Assembly jigs are designed to satisfy dimensional tolerance of the structure. Inspection criteria are established and applied to the manufacturing. Technical data about inspection items and methods are summarized as manufacturing specifications for the mass production of the UAV structure.

• Polymer(Korea)
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• v.39 no.1
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• pp.185-190
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• 2015

Since a transition from liquid crystal to crystal state is slow for the large photo-reactive liquid crystal molecules, it needs a long time for recrystallization of LC242 molecules when lowering the temperature of the liquid crystal. Although liquid crystals usually align along one direction, the directions of individual liquid crystal molecules are little different from one another with increasing temperature, resulting in changes of birefringence of the liquid crystal films. When the photo-reactive liquid crystals are photo-cured, faster curing kinetics and much larger curing degrees are observed for the films cured at the liquid crystal phase.