• Journal of the Korean Applied Science and Technology
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• v.22 no.3
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• pp.289-297
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• 2005

In order to improve resistant properties of water-borne acrylic pressure sensitive adhesives(PSAs) for automobiles, this study was carried out. Removable PSAs for automobiles were synthesized by emulsion polymerization of monomers, n-butyl acrylate(BA), n-butyl methacrylate(BMA), acrylonitrile(AN), acrylic acid(AA) and 2-hydroxyethyl methacrylate(2-HEMA), and AA and 2-HEMA could act as functional monomers for crosslink. Emulsion polymerization was carried out in a semi-batch type reactor. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, water resistance increased with the amount of BMA, however, the effect of BMA content on the water resistance was insignificant at a range of over 14 wt%. The water resistance also increased with the amount of functional monomers, AA and 2-HEMA. The prepared PSAs satisfied all the standard for automobiles except heat resistance. However, the heat resistance comes nearly up to the standard. Also, acid resistance, alkali resistance and smoke resistance of the prepared PSAs satisfied with the standard.

• The Journal of Advanced Prosthodontics
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• v.6 no.2
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• pp.121-125
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• 2014

PURPOSE. The purpose of this study was to investigate the bonding properties of denture bases to silicone-based soft denture liners immersed in isobutyl methacrylate (iBMA) and 2-hydroxyethyl methacrylate (HEMA) for various lengths of time. MATERIALS AND METHODS. Polymethyl methacrylate (PMMA) test specimens were fabricated (75 mm in length, 12 mm in diameter at the thickest section, and 7 mm at the thinnest section) and then randomly assigned to five groups (n=15); untreated (Group 1), resilient liner immersed in iBMA for 1 minute (Group 2), resilient liner immersed in iBMA for 3 minutes (Group 3), resilient liner immersed in HEMA for 1 minute (Group 4), and resilient liner immersed in HEMA for 3 minutes (Group 5). The resilient liner specimens were processed between 2 PMMA blocks. Bonding strength of the liners to PMMA was compared by tensile test with a universal testing machine at a crosshead speed of 5 mm/min. Data were evaluated by 1-way ANOVA and post hoc Tukey-Kramer multiple comparisons tests (${\alpha}$=0.05). RESULTS. The highest mean value of force was observed in Group 3 specimens. The differences between groups were statistically significant (P<.05), except between Group 1 and Group 4 (P=.063). CONCLUSION. Immersion of silicone-based soft denture liners in iBMA for 3 minutes doubled the tensile bond strength between the silicone soft liner and PMMA denture base materials compared to the control group.

• Journal of the Korean Chemical Society
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• v.22 no.5
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• pp.304-310
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• 1978

The relative permeabilities, distribution coefficients and diffusion coefficient of some salts which are important components in blood plasma through a poly(HEMA) membrane were measured. The crosslinker which was used for preparing the membrane was tetraethylene glycol dimethacrylate(TEGDMA), the weight percentage of the latter was about 2.8. We found that the diffusion coefficients ($D_m$) of the solutes decrease exponentially with increasing molecular weight, and also that $D_m$'s decrease linearly (except urea) with cylindrical radius (a). These facts were explained by a sieve pore flow model. The relative permeability and diffusion coefficient of urea at various temperature were larger than those of other solutes such as glycine, ${\beta}$-alanine, D-glucose, saccharose and maleic acid. The result indicates that the poly(HEMA) membrane might be suitable for hemodialysis application.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.579-588
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• 2007

Statement of problem: A tenderness of the dentin after tapering of teeth for dental prosthesis is a common phenomenon. In practice, the alternative desensitizer may be used for minor pain after tapering of teeth. Purpose: In this study, the desensitizers were used to investigate the affect decreasing of shear bond strength according to the use of various cement, such as resin, Glass Ionomer, and phosphate cement. Material and method: Three different desensitizers were used on this study Compositions of two dentin desensitizers were HEMA(hydroxyethylmethacrylate) and glutaraldehyde. The other one is oxalic acid. Three dentin desensitizers applied on 12 degrees taper teeth. Then, Ni-Cr crowns were bonded with Resin cement, Zinc Phosphate (ZPC) cement and Glass Ionomer (GIC) cement. 120 human premolar teeth were used for specimens. The specimens were divided into four group as the reference and the empirical each with thirty specimens, then further divided into 12 group according to type of desensitizers and cement types. The shear bond strength were measured by Instron multi task instrument. Results: According to the result, the measured shear bond strength in order from the weakest to the strongest in general was ZPC, Resin, and GIC. And it is found that the application of desensitizers on dentin surface does not affect the shear bond strength. Conclusion: Dentin desensitizers that alleviate or prevent a dentin tenderness, usually contains HEMA and glutaraldehyde compounds. Such desensitizers are widely used in clinical studies. By applying the dentin desensitizer on the exposed dentin surface, the dentin capillary are blocked and periodontal membrane and cementum can not be drawn in pulp cavity. Since HEMA and glutaraldehyde may cause harm to the pulp cavity, an alternative desensitizer was developed.

• Elastomers and Composites
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• v.54 no.4
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• pp.359-367
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• 2019

Poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels modified with various co-monomers, such as N-vinyl pyrrolidone (NVP), glycidyl methacrylate (GMA), and glycerol monomethacrylate (GMMA), were prepared to investigate the effect of adding a co-monomer on the water contents, surface wettability, and tensile modulus. These polymers were synthesized by thermal- and photo-polymerization in the presence of azobisisobutyronitrile (AIBN) and diphenyl(2,4,6-trimethylbenzoyl)-phosphineoxide (TPO) as the initiators. The characteristics of the hydrogels were analyzed via FTIR and UV/Vis spectroscopies, contact angle measurements, and tensile modulus measurements with UTM. Regarding the properties of water in the hydrogels, the ratio between free to bound water was investigated using differential scanning calorimetry (DSC). The effects of adding the co-monomers on the water content, surface wettability, and tensile modulus for soft contact lenses were also investigated. In the case of p(HEMA-co-NVP) hydrogels, the increase in the equilibrium water content (EWC) was primarily due to the increase in the bound water content. For p(HEMA-co-GMMA) hydrogels, an increase in free water content was the main reason for the increased EWC. In contrast, in the case of p(HEMA-co-GMA) hydrogels, a decrease in bound water content was observed to be the main factor that reduced the EWC. Photo-polymerized PHEMA hydrogels showed enhanced surface wettability and tensile modulus as compared to those produced via thermal polymerization.

• Textile Coloration and Finishing
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• v.8 no.3
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• pp.52-58
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• 1996

In order to study an applicable level for the graft finish of silk filaments and the characteristics of silk fabric, some sample fabrics were woven with grafted weft and the characteristics of sample fabrics were analyzed to evaluate the mechanical properites and the handle values according to the graft yield(%) of MMA and HEMA monomers on silk filaments. 1. The tensile properties were detected in the increase of linearity(LT) and the recovery in time of the increasing resilience(RT). 2. The bending properties were detected to have a lot of effect on the balance of bending rigidity(B) to hysteresis(2HB) according to the elastic relaxation of warp tension and the interlacing stress. 3. The shearing properities were detected to show the softness and the elastics in a case of the decrease in shearing rigidity(G) and hysteresis(2HG, 2HG5) according to the graft yields. 4. The compression properties were detected in the decrease of linearity(LC) and the uniformity of resilience(RC). It explains that the tendancies of compressible variation is not accepted. 5. The surface properities were detected to be affected by the surface forms of grafted silk filaments and the variation in the morphologies of interlacing sections. Considering the interlacing eveness, MMA grafted fabrics were accepted within the level of WOMEN'S THIN DRESS(KN-201-LDY) but HEMA grafted fabrics were not accepted. 6. The variation of handles were detected in the increase of total hand(TAV) within the levels of 65% of KOSHI and 82% of HARI on the average. 7. The handle fashions were detected in the nature of Habuta and Dechine from MAA graft but the nature of Fugi were shaped from HEMA graft in proportion to the graft yields.

• Polymer(Korea)
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• v.32 no.5
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• pp.470-477
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• 2008

Core shell binder of organic/organic pair that has two different properties within a particle were prepared by a step emulsion polymerization of methacrylate (MMA), styrene (St), ethyl acrylate (EA), butyl acrylate (BA), and 2-HEMA by using an water soluble initiator(APS) in the presence of an anionic surfactant (SDBS). Unwoven tensile strength of the core shell binder after processing and measuring the PSt/PMMA/2-HEM core shell with the binder is a value represents the highest was $10.75\;kg_f$/2.5cm, elongation measurements PEA/PBA core shell binder showed the highest value was 120.00%. In conclusion, using the core shell binders were able to control the mechanical properties such as tensile strength and elongation.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.259-265
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• 2006

We polymerized material of AA(Acrylic acid) and BMA(butyl methacrylate) to make up for the weak points of hydrogel contact lens. The synthesis process of silicone synthesis is as follows. Acrylate-PDMS(Polydimethylsiloxane)-Urethane prepolymer was composed after Diisocynate reacted with HEMA(2-hydroxyethylmethacrylate) under the catalyst and it reacted again with bis(hydroxyalkyl) terminated poly(dimethylsiloxane) with high oxygen transmissibility characteristics. HEMA(2-hydroxyethylmethacrylate) was used to make prepolymer that can be polymerized and the urethane was used to improve elasticity and oxygen transmissibility, copolymerization was performed with conventional hydrogel contact lens materials to make silicone hydrogel contact lens with higher oxygen transmissibility. For manufacturing of contact lens, We added BMA(Butyl methacrylate) with better elasticity and flexibility, and AA(Acrylic acid) with higher moisturizing to used contact lens materials. AIBN (Azobis2-methylpropionitrile) as initiator and EGDMA(Ethylene Glycol Dimethacrylat) as crosslinking agent were used and the lens with higher oxygen transmissibility and better moisturizing were manufactured complying with basic contact lens properties, which have several combination trial of each monomer characteristics. Compounding SN which included SILICONE, HEMA, NVP and EGDMA etc was showed by swelling ratio of 9.38% and water content of 23.7%. SN was showed by swelling ratio of 9.38%, water content of 23.7% and a visible ray transmissibility of 89%. SB which added BMA in the SN was showed by swelling ratio of 12.50%, water content of 18.56% and a visible ray transmissibility of 88%. SAB which added both AA and BMA in the SN was showed by swelling ratio of 8.33%, water content of 12.93% and a visible ray transmissibility of 88%.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.83-89
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• 2012

Purpose: This article was to study the optical and surface properties of soft contact lenses (SCL) exposed to eye make-ups. Methods: Rates of the light transmission of etafilcon A (HEMA based hydrogel lens) and lotrafilcon B (silicone based hydrogel lens) exposed to four different cosmetics over time were investigated. After cleansed with multi-purpose solution (MPS), rates of the light transmission and surface change of lens that were exposed to the cosmetics for 7 consecutive days were analyzed. Results: Visible light transmissions of all lenses exposed to cosmetics decreased to 93.35% (HEMA based hydrogel lens) and 90% (silicone based hydrogel lens) compared with those of the fresh SCLs, such as 97.8% and 96.4%, respectively. It was found that cosmetic residues from powder eye shadow and mascara attached to the lenses were not removed completely when cleansed with MPS. Especially with silicone based hydrogel lens, we found a decrease in visible light transmission of the lens and noticeable particles on lens surface imaged by SEM. Conclusions: Depending on types of eye make-ups and contact lens materials, make-ups were not completely eliminated with current cleansing methods and that caused a decrease in optical property and a change in surface property of the lenses.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.425-430
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• 1994

The effect of inhibitors and catalysts in the synthesis of 2-hydroxyethyl methacrylate(2-HEMA) was studied. As catalysts, triethylamine(TEA), $FeCl_3{\cdot}6H_2O$, $Cu(NO_3)_2{\cdot}2H_2O$, $AlCl_3$, $Na_2Cr_2O_7$were selected. p-Methoxyphenol (PMP) of aq. $NaNO_3$ solution was used as an inhibitor in polymerization. in aq. $NaNO_3$ inhibitor system, triethylamine (TEA), $FeCl_3{\cdot}6H_2O$, and $Na_2Cr_2O_7$, showed good catalytic effects. When p-methoxyphenol(PMP) was used as a polymerization inhibitor, the reaction was very sluggish and noneffective because the metal ion such as $Fe^{3+}$ or $Cr^{6+}$ was reduced by PMP. On the contrary, when aq. $NaNO_3$ was used as an inhibitor in polymerization, the reaction was very fast without deactivation of the metal catalysts.