• Fibers and Polymers
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• v.5 no.2
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• pp.89-94
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• 2004

N-Vinylcarbazole (VCZ) was solution-polymerized in tetrahydrofuran (THF) at 25, 35, and $45^{\circ}C$ using a room temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN); the effects of amount of solvent, polymerization temperature, and initiator concentration were investigated. On the whole, the experimental results corresponded to predicted ones. Room polymerization temperature using ADMVN proved to be successful in obtaining poly(N-vinylcarbazole) (PVCZ) of high molecular weight with small temperature rise during polymerization, nevertheless of free radical polymerization by azoinitiator. The polymerization rate of VCZ in THF was proportional to the 0.47 power of ADMVN concentration. The molecular weight was higher and the molecular weight distribution was narrower with PVCZ polymerized at lower temperatures. For PVCZ prepared in THF at $25^{\circ}C$ using ADMVN concentration of 0.00005 mol/mol of VCZ, weight-average molecular weight of 221,000 was obtained, with polydispersity index of 2.05, and degree of lightness converged to about 99%.

• Korean Journal of Materials Research
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• v.28 no.12
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• pp.696-701
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• 2018

This study is carried out to evaluate the commercial feasibility of the room temperature and thermal polymerization method as a lens manufacturing method. All samples are found to be transparent after polymerization, thereby indicating that their physical and surface properties are suitable for hydrogel ophthalmic lenses. The optical and physical properties of the lenses are compared. The water content of the samples that are prepared via a room temperature polymerization process decreases with the addition of MMA as compared to the water content of the samples that are prepared via thermal polymerization. When MMA and DMA are used as an additive for improving functionality, the wettability of the lenses increases. By measuring the AFM, the surface roughness is shown to improve more than MMA and DMA. Therefore, it is judged to be an appropriate process for manufacturing hydrogel lenses with high functionality.

• Journal of Technologic Dentistry
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• v.35 no.2
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• pp.127-136
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• 2013

Purpose: In order to find out the impact of changes in polymerization conditions of orthodontic acrylic resin on maximum load. Methods: While maintaining mixing ratio 3:1 of polymer and monomer in spray-on way in the production condition of polymerization temperature $25^{\circ}C$ or $37^{\circ}C$ for 10 minutes or 30 minutes of polymerization time by pressure $3kfg/cm^2$ or $6kfg/cm^2$ in the lab maintaining $25^{\circ}C$ of room temperature, the change in maximum load rise rate was tested by producing 5 acrylic resin specimens for orthodontics per group to meet the standards of $25mm{\times}2mm{\times}2mm$ and using INSTRON with the 3rd bar 2mm in diameter and parallel support bending device of $15{\pm}0.1mm$ as test equipment showing 30.00mm/min of crosshead speed, $50{\pm}16$ N/min of load ratio in the laboratory of $24^{\circ}C$ room temperature and as a result, the following results were obtained. Results: 1. When increasing pressure from $3kfg/cm^2$ to $6kfg/cm^2$, maximum load was lowered by -4.285%. 2. When increasing polymerization time from 10 minutes to 30 minutes, maximum load rose by 3.848%. 3. When increasing polymerization temperature from $27^{\circ}C$ to $37^{\circ}C$, maximum load rose by 5.854%. Conclusion: Considering the above test results that polymerization time and polymerization temperature when polymerizing acrylic resin for orthodontics according to changes in working conditions had an impact on the rate of rise of maximum load values but the rate of rise was lowered when increasing pressure from $3kfg/cm^2$ to $6kfg/cm^2$, we came to a conclusion that high pressure more than necessary does not affect the rate of rise of maximum load.

• Fibers and Polymers
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• v.5 no.1
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• pp.75-81
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• 2004

To obtain high molecular weight (HMW) poly(methyl methacrylate) (PMMA) with high conversion, methyl methacrylate (MMA) was polymerized in suspension using a room temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN), and the effects of polymerization conditions on the polymerization behavior of MMA and the molecular parameters of PMMA were investigated. On the whole, the experimental results well corresponded to the theoretically predicted tendencies. These effects could be explained by a kinetic order of ADMVN concentration calculated by an initial rate method and an activation energy difference of polymerization obtained from the Arrhenius plot. Suspension polymerization at 25℃ by adopting ADMVN proved to be successful in obtaining PMMA of HMW (number-average degree of polymerization (P/sub n/): 30,900-36,100) and of high yield (ultimate conversion of MMA into PMMA: 83-93 %) with diminishing heat generated during polymerization. The P/sub n/ and lightness were higher and polydispersity index was lower with PMMA polymerized at lower temperatures.

• The Journal of the Korean dental association
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• v.11 no.1
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• pp.37-40
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• 1973

The auther measured exothermic tempreature of the 5 kinds of direct resins during polymerization. Direct resins were mixed into the rubber cup(550-600㎣ in volume) with grass rod at room temperature (23.6℃) for 30 seconds and thermometer was placed approximately at the geometric center of the resin mass in the rubber cup. Polymer-monomer ratio was determined by instruction of the packages. The results were as follows. 1) The heat generated during polymerization was under 47.3℃. 2) The time at which the highest temperature is reached during polymerization was within 20.5 minutes. 3) Slow curing resins produced lower heat than quick curing resins and quick curing resins presented higher temperature than slow curing resins. 4) The highest temperature was sustained momentarily.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.68-74
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• 2005

In this work, polymerization conditions of the gel polymer electrolyte (GPE) were studied to obtain better electrochemical performances in a lithium-ion polymer battery. When the polymerization temperature and time of the GPE were 70$^{\circ}C$ and 70 min, respectively, the lithium polymer battery showed excellent a rate capability and cycleability. The TMPETA (trimethylolpropane ethoxylate triacrylate)/TEGDMA (triethylene glycol dimethacrylate)-based cells prepared under optimized polymerization conditions showed excellent rate capability and low-temperature performances: The discharge capacity of cells at 2 Crate showed 92.1 % against 0.2C rate. The cell at -20 $^{\circ}C$ also delivered 82.4 % of the discharge capacity at room temperature.

• Bulletin of the Korean Chemical Society
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• v.18 no.12
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• pp.1296-1301
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• 1997

Polymerization of terminal alkynes (phenlacetylene and 4-ethynyltoluene) catalyzed by water soluble rhodium (Ⅰ) complex, RhCl(CO)(TPPTS)2 (TPPTS=m-P(C6H4SO3Na)3) (1) selectively produces cis-transoid polymers at room temperature in homogeneous solution of H2O and MeOH as well as in biphasic solutions of H2O and CHCl3. The rate of polymerization is higher in H2O/MeOH than in H2O/CHCl3. The iridium analog, IrCl(CO)(TPPTS)2 (2) shows catalytic activity for the polymerization of phenylacetylene only at elevated temperature to give trans-polymers. The polymerization rate increases significantly when the trimethylamine N-oxide (Me3NO) was added to the reaction mixtures. The electronic absorption spectra of the cis-transoid polymers show three absorption bands whereas the trasn-polymers show only one absorption band. It seems that the electronic absorption bands depend on the configuration of the polymers.

• Structural Engineering and Mechanics
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• v.2 no.4
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• pp.383-393
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• 1994

The residual stress distribution in a unidirectional graphite/epoxy laminate induced during the fabrication process is investigated at the microstress level within the scope of linear viscoelasticity. To estimate the residual stresses, the fabrication process is divided into polymerization phase and cool-down phase, and strength of materials approach is employed. Large residual stresses are not generated during polymerization phase because the relaxation modulus is relatively small due to the relaxation ability at this temperature level. The residual stresses increase remarkably during cool-down process. The magnitude of final residual stress is about 80% of the ultimate strength of the matrix material at room temperature. This suggests that the residual stress can have a significant effect on the performance of composite structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.139-142
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• 1995

Polyimide(PI) thin films are fabricated by vapor deposition polymerization(VDP) from PMDA and DDE. The IR spectrum show that PAA the films are changed into PI films by curing. The activation energy of PI films is estimated to be 0.32 [eV] at the electric field of 0.133 [Mv/cm]. The resistivity is about 4.5${\times}$10$\_$16/ [$\Omega$$.$cm] at room temperature.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.271-273
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• 1991

Poly (N-vinylcarbazole) was obtained spontaneously by 1,1,2,2-tetracyanocyclopropylstyrene(1) in polar solvents such as dichloromethane and acetonitrile at room temperature. The polymerization reactions were faster in more polar solvent and were not proceeded in less polar solvents such as chloroform and diethyl ether. The formation of poly (N-vinylcarbazole) was explained by bond-forming initiation theory, in which the initiating species are zwitterionic tetramethylene intermediates.