• Journal of Korean Society of Forest Science
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• v.87 no.4
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• pp.601-610
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• 1998

This study was carried out to investigate the possibility of supplemental UV-B application to the hardening phase of container-grown Betula platyphylla seedlings. The containerized seedlings were grown in a growth chamber for four months and then treated with UV-B(UV-$B_{BE}$ $3.2KJ\;m^{-2}\;day^{-1}$ and $5.2KJ\;m^{-2}\;day^{-1}$) radiation and water stress regime(irrigation in one week interval) for four weeks. The differences in growth and physiological responses of the seedlings before and after the treatments were analyzed. UV-B radiation and water stress reduced height growth and leaf dry mass accumulation of the seedlings. The root collar diameter growth was reduced by UV-B radiation but increased by water stress. The reduction in leaf dry weight by UV-B radiation and water stress reduced T/R ratio of the seedling. The reduction in T/R ratio was the most apparent by water stress. Chlorophyll index observed by a chlorophyll meter was the lowest in the $5.2KJ\;m^{-2}\;day^{-1}$ of UV-B radiation, and those in the $3.2KJ\;m^{-2}\;day^{-1}$ and water stress were similar. UV-B radiation and water stress reduced both water content in the seedlings and leaf water potential, and increased leaf osmatic pressure. The water content of leaves and shoots was reduced more rapidly by UV-B radiation than by water stress treatment. In conclusion, growth responses and physiological changes in water relation by supplemental UV-B radiation which was applied to the hardening phase of container-grown Betula platyphylla seedlings were similar results to the water stress treatment.

• Journal of Adhesion and Interface
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• v.13 no.1
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• pp.38-44
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• 2012

Surface properties and curing behavior of UV-initiated photopolymerization with and without wax have been investigated by pendulum hardness, pencil hardness, gloss, photo-differential scanning calorimetry (photo-DSC) and SEM. In addition, the influence of wax type (paraffin wax, PE wax) on the various properties of UV cured films was studied. The results showed that the wax type was the significant factor affecting gloss and surface hardness of UV cured films. Specially, the photo-DSC results showed that ${\Delta}H$ for the UV cured films containing paraffin wax was higher than the corresponding values for the formulation without wax and with PE wax. The observed results clearly demonstrate that the photopolymerization of UV curing with paraffin wax in an air atmosphere is less inhibited by the oxygen compared to UV curing without wax and with PE wax.

• Journal of Adhesion and Interface
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• v.14 no.4
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• pp.167-174
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• 2013

In this study, Ultraviolet (UV) curable urethane acrylates for ink binder was prepared by reaction of IPDI, polyether polyol and HEA. The UV curing behavior of compositions with HEA/PETA ratio on UV irradiation time was investigated by FT-IR spectrophotometer, probe tack tester and Photo-DSC. Conversion % and gel content were increased with increasing UV irradiation time, but probe tack was decreased. Storage modulus, tensile strength and decomposition temperature were increased as PETA content increased. In case of HEA/PETA ratio was 30/70, adhesion property of UV-cured composition on PMMA sheet was excellent.

• Journal of Adhesion and Interface
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• v.13 no.4
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• pp.156-162
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• 2012

Polyurethane (PU)/organoclay nanocomposites were prepared by mixing UV curable urethane acrylate oligomer with organoclay, and a subsequent curing by UV irradiation. As organoclays, commercially available Cloisite 20A (C20A) and acrylsilane modified C20A were used. XRD and TEM analyses revealed that the UV cured PU/clay nanocomposites formed intercalated nanocomposites, and acrylsilane modified C20A are dispersed more finely than unmodified C20A in PU matrix. DMTA, pencil hardness and adhesion test onto PET substrate showed that the clay nanolayers induced an increase in the properties, and the enhancement in the properties was more pronounced in the PU/acrylsilane modified C20A nanocomposites than in the PU/unmodified C20A nanocomposites. It was also observed that the PU/surface modified clay nanocomposites showed remarkably lower shrinkage upon UV curing than the unfilled PU. The nanocomposites showed excellent optical transparency but lower gloss as compared to unfilled PU.

• Journal of Convergence for Information Technology
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• v.7 no.1
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• pp.43-48
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• 2017

The design trend is changed with the times. The design trend of recent 21 century is eco-friendly design. The optical illusion design is a new trend of digital convergence era. In this study, optical illusion patterns were designed for furniture with eco-friendly UV-curable resin. The micro-patterns of optical illusion design were fabricated with the micro-mold which was mastered using a semiconductor micro-fabrication process by photolithography technique. The micro-patterns of optical illusion design were manufactured on PET film with a roll-to-roll process using a UV-curable resin. The manufactured PET film of optical illusion micro-pattern exhibits hologram effect, optical illusion effect, and texture of metal with the backside digital printing of metal tone. The furniture of new design concept so-called emotional furniture was manufactured with the various optical illusion design patterns. The optical illusion design patterns by UV mold prospect a new trend of interior design materials.

• Journal of Adhesion and Interface
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• v.9 no.2
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• pp.32-37
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• 2008

A series of UV-curable powder coatings with different contents of photoinitiator (0.5 wt%, 1 wt%, 2 wt%) were formulated and measured gel content, tensile strength of cured film. Heat-sensitive substrates such as MDF, plywood and PVC were coated UV-curable powder and cured coatings were measured physical properties by pendulum hardness tester, glossmeter, pull-off adhesion tester. With increasing photoinitiator content, adhesion force between coating and substrate decreased because of crosslinking density increasing. The results of pendulum hardness was not significantly changed but gloss was changed according to different substrates. Adhesion of UV-curable coatings was enough to apply for heat-sensitive substrates. From these results, we concluded that contents of photoinitiator was a effective factor in UV-curable powder coatings. UV-curable coatings was a portential candidate for heat-sensitive substrates.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.626-631
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• 2017

Transparent plastic substrates require an improvement in properties such as surface hardness and thermal stability for optical applications. In this study, UV-curable organic/inorganic hybrids were synthesized to improve those properties. In order to make the optimum dispersion of inorganic component into the organic matrix, an in situ synthetic method was applied based on sol-gel reaction. Dispersion of the inorganic component in the organic urethane acrylate matrix was improved by using a proper combination of sol-gel reaction and fast UV-curing resulting in the formation of the transparent coating layer. Various alkoxy silanes were employed to vary both the degree of curing and coating properties of UV-curable organic/inorganic hybrids. UV-cured organic/inorganic hybrid coatings showed an improved surface hardness and thermal resistance depending on the content of inorganic component.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.754-761
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• 2017

UV-curable hydrophilic coating solutions were prepared by mixing colloidal silica dispersed in alcohol with an acrylic monomer, pentaerythritol triacrylate (PETA). Hydrophilic coating films were also prepared by spin coating the hydrophilic coating solutions on PC substrates and UV curing for 10 minutes subsequently. The effect of the amount of colloidal silica in the coating solutions, which was varied from 10 g to 50 g, was investigated on the hydrophilic properties of UV-cured coating films. The results showed that the amount of colloidal silica had a great influence on the hydrophilic properties of UV-cured coating films and the coating film prepared with 30 g of colloidal silica showed a lowest contact angle of $37^{\circ}$ and an excellent pencil hardness of H.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.8
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• pp.24-28
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• 2009

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.76-81
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• 2008

UV curable pressure sensitive adhesive (PSA) was made by blending the di-functional or hexa-functional urethane-acrylate oligomer with synthesized acrylic PSA. The change of adhesive property and removability were investigated at various oligomer contents under each oligomer. As the content of oligomer increased, the peel strength was increased before UV irradiation, but it was decreased after UV irradiation. Also, it was observed that the peel strength increased with decrease of storage modulus (G'), and that loss factor (tan ${\delta}$) of the adhesive material affected the adhesive properties and removability.