• Elastomers and Composites
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• v.44 no.1
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• pp.63-68
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• 2009

Recently, much attention has focused on the permanent deformation of roads in hot summer and cracks in cold winter, which are detrimental to safe driving. This leads to necessity of modification of asphalt to resist those deformation. In this study, a type of modified asphalt was prepared by addition of a photoinitiator which is activated by ultraviolet lay. The mechanical and rheololgical properties of photoinitiator-modified asphalt were examined using UTM and rheometer. Results showed that the modified asphalt was effected by ultraviolet and thus tensile strength and storage modulus increased, due to molecular attraction, with initiator content and irradiation dose. Thermal analysis showed less weight loss upon photoinitiator-modification and this indicated that the molecular attraction is the result of cross linking reaction between asphalt molecules induced by photoinitiator. According to long term ultraviolet curing test, properties of the photoinitiator-modified asphalt did not decrease or even increase for 20 years. This indicates that useful life of the asphalt could be extended by addition of photoinitiator.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1208-1211
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• 2004

When irradiated with visible light in HPDLC, photoinitiator and coinitiator produce a radical for photopolymerization. According to the kinds of photoinitiator and coinitiator, quantity and rate of produced a radical is different. It is influence on photopolymerization rate relate on diffraction efficiency. Thus, this paper is about the effect of photoinitiator/coinitiator combinations in terms of diffraction efficiency and real-time first order diffraction efficiency.

• Polymer(Korea)
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• v.39 no.2
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• pp.256-260
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• 2015

The addition of montmorillonite (MMT) in the UV curable polyurethane diacrylate based resins was investigated to fabricate nanocomposites with improved mechanical properties and water sorption behavior using different photoinitiator systems. As a result, it was observed that 1 wt% of clay loading fairly improved tensile resistance and water uptake behavior. It can be also confirmed that dual photoinitiator system consisted of benzyldimethyl ketal and bisacyl phosphine oxide exhibited enhanced energy absorption band 340~450 nm even with 3 wt% of MMT concentration, which may affect the curing behavior of nanocomposite especially in our UV lamp system.

• Journal of Technologic Dentistry
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• v.23 no.2
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• pp.49-59
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• 2002

The photopolymerization efficiency and surface hardness of composite resin containing 1,2-phenylpropanedione (PD) and diacetyl (DA) as photoinitiators were studied by IR and Vickers hardness and the results were compared with that of camphorquinone (CQ). Relative photopolymerization efficiency of the photoinitiators increased in the order of DA < CQ < PD. Vickers hardness of composite resin containing the photoinitiators increased in the order of CQ < PD < DA. Thus, PD is a new visible light photoinitiator for dental composite resin with higher photopolymerization efficiency and surface hardness than that of CQ. Mechanical properties such as Vickers hardness, diametral tensile strength, and flexural strength of the experimental resin composite prepared by addition of the photosensitizer into a resin of bis-GMA improved with increasing the photosensitizer content and irradiation time. The resin composite of bis-GMA containing DA or PD shows better mechanical properties than that of CQ.

• Journal of Photoscience
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• v.5 no.2
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• pp.63-67
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• 1998

New photoinitiator systems of dimethylphenacylsulfonium butyltnphenylborate (DMPSB) as a donor-acceptor initiator and styryl dyes have been investigated for free radical polymerization of an acrylate with visible lasers (488, 514 and 647 nm). DMPSB was able to be sensitized by many styryl dyes. When polymerized with pentaerythrithol triacrylate, the sensitivity value of the photosensitive layer containing DMPSB was higher than that of an tetrabutylammonium butyltnphenylborate (TBAB) as an electron donating initiator or a dimethylphenacylsulfonium tetrafiuoroborate (DMPS) as an electron accepting initiator. The sensitivity values of the photosensitive layer containing the photoinitiator systems had a close relation to the free energy changes between the excited singlet styryl dyes and DMPSB.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.147-153
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• 1997

Bismaleimides(BISMI) containing ester linkages were prepared by the chlorinated N-(p-carboxyphenyl)maleimide and N-(p-hydroxyphenyl)maleimide. The photosensitive properties of BISMI were investigated via changes of the irradiation time. Benzil dimethyl ketal was used as a photoinitiator. The effect of photoinitiator onto BISMI increase in average as increasing photoinitiator concentration and irradiation time. The yield of residual film and image pattern and resolution also measured and discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.396-398
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• 2005

Effects of such factors as polymerization temperature and a newly synthesized oligomeric photoinitiator(PEDI380) on the electro-optic characteristics of polymer/LC composite films prepared by the UV-curing method were investigated. The polymer-dispersed liquid crystal cells were made with oligomeric photoinitiator PEDI380 by UV-curing method exhibited both low driving volta ge($V_90$) and high contrast ratio under optimum formulation condition.

• 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.

• Elastomers and Composites
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• v.45 no.3
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• pp.217-222
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• 2010

Paved roads are suffered from the permanent plastic deformation in hot summer and cracks in cold winter, which are detrimental to safe driving. This leads to necessity of modification of asphalt to resist those deformation. In this study, two kinds of modifiers were examined; organic polymers and a photoinitiator which is activated by ultraviolet lay. The mechanical and rheololgical properties of modified asphalts were examined using UTM and rheometer. Results showed that the properties were varied depending on the types of polymer and irradiation time. UV irradiation increased the tensile strength and storage modulus of thermoplastic polymer-modified asphalt, however UV was not effective on thermoset polymer. According to long term ultraviolet curing test, properties of the polymer/photoinitiator-modified asphalt did not decrease, but rather increase for 20 years. This indicates that the useful life of the asphalt could be extended by addition of photoinitiator.

• Journal of Powder Materials
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• v.26 no.4
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• pp.327-333
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• 2019

In this study, a process is developed for 3D printing with alumina ($Al_2O_3$). First, a photocurable slurry made from nanoparticle $Al_2O_3$ powder is mixed with hexanediol diacrylate binder and phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide photoinitiator. The optimum solid content of $Al_2O_3$ is determined by measuring the rheological properties of the slurry. Then, green bodies of $Al_2O_3$ with different photoinitiator contents and UV exposure times are fabricated with a digital light processing (DLP) 3D printer. The dimensional accuracy of the printed $Al_2O_3$ green bodies and the number of defects are evaluated by carefully measuring the samples and imaging them with a scanning electron microscope. The optimum photoinitiator content and exposure time are 0.5 wt% and 0.8 s, respectively. These results show that $Al_2O_3$ products of various sizes and shapes can be fabricated by DLP 3D printing.