• Journal of the Korean Graphic Arts Communication Society
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• v.13 no.1
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• pp.93-104
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• 1995

Liquid crystal-polymer composite(LCPC) films promising new materials for both projection displays and vision product. LCPC films consist of a continous liquid crystal phase embedded in a three- dimensional network of polymer matrix. The liquid crystal in these LC phases can be elecrtrically switched giving rise to an opaque scattering off-stats and a transparent, non-scatting on- stats. In this work. a premixture is composed of LC, UV-curable monomer and photonitiator. LCPC films are formed by photopolymerization induced phase separation from this premixture. In conclusion, structure and electro-optical properties of LCPC films strongly depends on the selection of monomer, LC content and curing rate.

• Journal of the Korean Graphic Arts Communication Society
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• v.13 no.2
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• pp.19-32
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• 1995

Liquid crystal-polymer composite(LCPC) films are promising new materials for both projection displays and vision products. LCPC films consist of a continuous liquid crystal phase embedded in a three- dimensional network of polymer matrix. The liquid crystal in these LC phases can be electrically switched giving rise to an opaque scattering off-state and a transparent, non- scattering on-state. In this work, a premixture is composed of LC, UV-curable monomer and photonitiator. LCPC films are formed by photopolymerization induced phase separation from this premixture. In conclusion, structure and electro-optical properties of LCPC films strongly depends on the selection of monomer, LC content and curing rate.

• Journal of the Korean Graphic Arts Communication Society
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• v.11 no.1
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• pp.17-29
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• 1993

As inverstigating the influence of monomers and photoinitiator in the polymerization rate of photopolymerization by using IR spectroscopy, photopolymerizations initiated by ultraviolet radiation are characterized by the presence of an autoacceleration in the polymerization rate as the reaction proceeds. The conversion for the end of the autoacceleration varies considerably depending on the monomer and reaction condition which determines coil size and viscosity. In UV curable systems, the autoacceleration begins at only a few percent conversion and continues to 40% in HEA solution and 60% conversion in EHA solution. The polymerization ate in HEA solution increased as follow; DMHA > HCPK > DMPA and could be explained by the interaction between the initiating radical and HEA monomer and the size of the photodissociated radical of initiator. But the tendency of autoacceleration in EHA solution is almost independent on initiator.

• Polymer(Korea)
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• v.32 no.2
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• pp.138-142
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• 2008

Molecularly imprinting technology is an effective method to prepare a synthetic material with a high selectivity to a target molecule. In this study, a molecularly imprinted polymer (MIP) was synthesized via UV-polymerization using theophylline and UV-curable polyester-acrylate resin as a template molecule and a crosslinker, respectively. To elucidate the effects of functional monomer type on the performance of the MIP, each MIP was synthesized using mathacrylic acid, acrylic acid, and acryl amide as functional monomers. Each MIP showed higher rebinding capacity to theophylline than its corresponding non-imprinted polymer (NIP). The MIP synthesized using mathacrylic acid as a functional monomer showed the highest rebinding capacity to theophylline. The selectivity of the MIP was investigated using a solution with caffeine having a very similar structure to theophylline. The binding performance of the MIP to theophylline decreased when distilled water was used as a solvent, which has more polarity than chloroform.

• Polymer(Korea)
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• v.33 no.5
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• pp.496-500
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• 2009

Optically compensated bend liquid crystal display (OCB-LCD) has many application fields owing to its fast response time and wide viewing angle. However, in order to operate the OCB-LCD in bend state, this device needs quick transitions from the initial splay state to bend state. Unlike conventional approach using transient high voltage for the transition, the OCB-LCD with high surface tilt angle, which was achieved by polymerization of UV curable reactive mesogen monomer under certain voltage, was manufactured and the cell showed bend state initially. Electro-optic and electrical characteristics of the cell were analyzed. The cell shows a fast response time owing to high surface pretilt angle and very low residual DC less than 0.1 V although another polymer layer is formed above polymer alignment layers.

• Journal of the Korean Graphic Arts Communication Society
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• v.22 no.1
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• pp.39-52
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• 2004

A novel evaluation method is investigated for measuring the ability of acid amplification of acid amplifier. The method is based on the measurement of conductivity change by the acid generation according to UV radiation. It is found that the decrease of conductivity is caused by photopolymerization of epoxy monomer during UV curing process of ink film and the by the rate of UV curing. In this paper, the novel acid amplifiers were synthesized and measured thermal stability by means of DSC. It was found that mono-type acid amplifiers were more stable than di-type. It is possible to make the dynamical evaluation the curing rate of UV curable ink in curing process by this method.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.209-213
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• 2006

Relationship between printability and rheological properties of UV flexographic (flexo) inks were investigated. UV flexo suspensions of carbon black in liquid medium having various binding materials such as acylate pre-polymer, di/multi-functional monomer, and diluents, were used as sample inks. Inks were characterized on a rheometer in terms of steady and dynamic behaviors. To understand the rheological properties of UV flexo inks, we must determine the specific rheological properties of chemical and/or physical interactions of their components (pigments, functional monomers, and pre-polymers). In particular, we discussed the influence of multi-functional monomers and the relationship between the rheological properties and transient networks formed by carbon black. In this study, we investigated the interrelationships between rheological properties of UV flexo inks and chemical and/or physical interactions of their components. To investigate correlations between the printability and the rheological behaviors induced by interfacial interactions between ink compositions, we carried out rheological tests of UV ink suspensions. The results were compared with printing tests so as to find out the relationship between printability and rheological properties of ink.

• Journal of Adhesion and Interface
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• v.20 no.1
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• pp.15-22
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• 2019

In this study, polybutadiene based di-functional urethane acrylate oligomer (PB-UAO) were synthesized from polybutadiene diol and isophorone diisocyanate. And then, pressure sensitive adhesive films were prepared by mixing with synthesized oligomer, tri-functional acrylate monomer (Tris(2-acryloyloxyethyl) isocyanurate (TAOEIC) or Trimethylolpropane triacrylate (TMPTA) or Pentaerythritol triacrylate (PETA)), mono-functional acrylate monomer (Stearyl acrylate) and UV initiators. Effects of types and contents of trifunctional acrylate monomers on peel strength, tensile strength, elongation, thermal stability and water absorption property were studied. As the contents of tri-functional acrylate monomer increased, and as the molecular weight of tri-functional acrylate monomer decreased, peel strength, elongation and water absorption showed a tendency to decrease whereas tensile strength and thermal stability showed a tendency to increase.

• Journal of the Korean Ceramic Society
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• v.54 no.6
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• pp.470-477
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• 2017

Ceramic processing to fabricate 3D complex ceramic structures is crucial for structural, energy, environmental, and biomedical applications. A unique process is ceramic stereolithography, which builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This approach directly writes layers in liquid ceramic suspension and allows one to fabricate ceramic parts and products having more accurate, complex geometries and smooth surfaces. In this paper, both UV curable materials and processes are presented. We focus on the basic material principles associated with free radical polymerization and rheological behavior, cure depth and broadening of cured lines, scattering at ceramic interface and their corresponding simulation. The immediate potentials for ceramic AM to change industry fabrication are also highlighted.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.2
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• pp.113-124
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• 2000

It is well known that the characteristics of liquid crystal polymer composite(LCPC) films are possessed of large-area and flexible display, polarizer free, high contrast, wide angle of visual filed and high responsiveness. In this study, we have investigated to the best optimal mixing rates chiral nematic liquid crystals and UV-curable resins having different properties acrylate moleculars. The purpose of this study has been the development of new functional application with liquid crystal polymer composite films. For example the films were applied a new thermal sensor. In results, best phase separation behaviors turned out liquid crystal/monomer/oilgomer mixture system.