• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.2
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• pp.13-20
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• 2013

In this study, two biodegradable polymer(PLA, PBS) emulsions were treated on agricultural packaging paper such as fruit bagging paper. Water-repellency, mechanical properties, and SEM image with thermal aging were measured on the emulsion treated fruit bagging paper. Biodegradable polymers(such as poly lactic acid, poly butylene succinate) emulsion treated fruit bagging paper had higher water-repellency and strength than other water-repellent(such as acrylic repellent, linseed oil and paraffin wax) treated fruit bagging paper. According to FE-SEM results of polymer emulsion coated fruit bagging paper, the colloidal particles of emulsion after thermal treatment (looks like being) were adhered to the fibers. Thus, using biodegradable polymer emulsion is expected to protect a fruit for a long time.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.123-129
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• 1988

The purpose of this study was to evaluate the bond strength of glassionomer cement against cut dentin surface which was treated with various surface cleaning agents. 48 freshly extracted human 3rd molars were ground flat through the enamel into the dentin using 600 grit silicone carbide paper under a flow of water. The were divided into four groups by the following cleaning procedure on cut dentin surface; Group I : No surface treatment after grinding with 600 grit silicone carbide paper as control group Group II : Surface treatment with 50% citric acid for 30 seconds. Group III : Surface treatment with 37% phosphoric acid for 30 seconds. Group IV : Surface treatment with 10% poly acrylic acid for 30 seconds. The specimens in 4 groups were immersed in distilled water at $37^{\circ}C$ for 24 hours before testing after cleanising with water-spray and drying with air. Bond strength was measured with Instron Universal Testing Machine (Autograph S-100, Shimadzu, Kyoto, JAPAN). The results were as follows: 1. The bond strengths of group II, III & IV were not seemed to be shown more significant improvement than a group I. 2. The bond strengths in groups which were treated with 50% citric acid, 37% phosphoric acid and 10% polycrylic acid, were ranked 24.70kg/$cm^2$, 22.02kg/$cm^2$ and 31.13kg/$cm^2$, but its difference was not significant, statistically.

• Clean Technology
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• v.18 no.1
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• pp.57-62
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• 2012

Aqueous poly (vinyl alcohol) (PVA) solution was modified by using hydrophobic vinyltriethoxysilane (VTEOS) and then adding different amounts of poly (acrylic acid) (PAA) to the resulting solution. Thermal and mechanical properties, contact angle, water vapor transmission rate (MVTR) and oxygen gas transmission rate ($O_2TR$) of the film samples fabricated by these solutions were investigated. The glass transition temperature (Tg) of the VTEOS-modified films was sightly increased and the value remained unchanged according to the amount of PAA. The tensile strength of the VTEOS-modified films was found to be 9.48~10.72 $kg/mm^2$ which showed no significant difference compared with that of PVA. The film prepared with VTEOS-modified PVA/PAA (= 90/10), of which the swelling and solubility were measured to be 198% and 0%, respectively, showed improved water-resistance. The MVTR and $O_2TR$ for the PET film (thickness 50 ${\mu}m$) coated with VTEOS-modified PVA/PAA (= 90/10) film (thickness 2.5 ${\mu}m$) were measured to be 11.04 $g/m^2/day$ and 3.1 $cc/m^2/day$, respectively.

• Journal of the Korean Chemical Society
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• v.56 no.6
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• pp.725-730
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• 2012

HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate; cross-linker), MMA (methyl methacrylate) and AA (acrylic acid) were copolymerized with ethyl gallate and propyl gallate as additives in the presence of AIBN (2,2'-azobisisobutyronitrile; initiator). The measurement of physical properties of the produced copolymers exhibited that refractive index, water content, visible transmittance, tensile strength, and contact angle were in the range of 1.433-1.435, 38.71-38.99%, 85.4-88.8%, 0.2468-0.2740 kgf and $49.77-36.29^{\circ}$, respectively. The transmittances of the copolymers were measured to be in the range of 49.0-7.4% and 71.0-43.4% for UV-B and UV-A, respectively, indicating that the copolymers have UV-blocking effect. The produced copolymers containing ethyl gallate and propyl gallate satisfied the basic physical properties required for the fabrication of hydrogel contact lenses. The copolymers showed an increase of wettability and UV-blocking effects while having no significant change in water content compared to the gallate-free copolymers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.4
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• pp.168-172
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• 2010

Superhydrophilic thin film consisted of positively charged poly (allylamine hydrochloride) (PAH) and negatively charged poly (acrylic acid) (PAA) was fabricated by a layer-by-layer (LBL) self-assembly. Glutaraldehyde (GA) was used in order to increase an adhesion hardness by amine-aldehyde reaction. The surface morphology, thickness, transmittance, water contact angle and adhesion hardness of PAH/PAA thin film with or without GA were measured. The adhesion hardness of PAH/PAA thin film with GA deposition increased over 2 times although the film thickness of PAH/GA/PAA decreased than that of PAH/PAA thin film. The increase of adhesion hardness by amine-aldehyde reaction between PAH and GA was measured by fourier transform infrared (FT-IR) spectroscopy. Fabricated PAH/PAA and PAH/GA/PAA thin films showed water contact angel under $5^{\circ}$ and high transmittance over 91.3% at 550 nm.

• Polymer(Korea)
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• v.33 no.1
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• pp.45-51
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• 2009

Water soluble adhesive was polymerized from butyl acrylate (BA), methyl methacrylate (MMA) and one of various functional monomers such as acrylic acid (AA), 2-hydroxylethyl methacrylate (2-HEMA), glycidyl methacrylic acid (GMA) and acrylamide (AAm). The amount of the functional monomers was 1$\sim$5 wt%/monomer. In order to improve the adhesive power, a substrate was treated using atmospheric flat plasma method. The adhesive power was improved by the addition of the functional monomers with an order of AA> 2-HEMA> GMA> AAm. The holding power of the adhesives, which is related with the thermal properties of the adhesives, increased with the amount of the functional monomers. The effectiveness in improving the holding power has an order of AA > AAm > GMA > 2-HEMA. By treating a substrate with atmospheric flat plasma method, the adhesives containing each of AA, 2-HEMA, GMA and AAm showed the increases of the final adhesion strength by 9.1, 9.4, 9.4, and 1.8%, respectively. In conclusion, the mechanical properties such as adhesive power and holding power could be controlled by introducing.

• Journal of Adhesion and Interface
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• v.1 no.1
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• pp.23-29
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• 2000

Surface modification of hydrophobic polymeric materials to be hydrophilic or to have specific functional groups is of great importance for a diversity of applications of the materials. In this study, polyethylene (PE) film surfaces were modified by vapor phase photografting of hydrophilic vinyl monomers with different functional groups. The functional monomers were introduced on PE films by introducing the monomers in vapor phase using a vapor phase photografting apparatus designed by our laboratory. Functional monomers used were acrylic acid (negatively chargeable), acrylamide and allylalcohol (neutral), and allylamine and N,N-dimethyl aminopropyl acryamide (positively charged). The functional monomer-grafted PE film surfaces were characterized by the measurement of water contact angles and the attenuated total reflectance Fourier-transform infrared spectroscopy. The vapor phase photografting seems to be effective means for introduction of various functional groups onto polymeric substrates.

• Clean Technology
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• v.19 no.2
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• pp.140-147
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• 2013

In this study, chemical demulsification and electrical treatment methods were investigated for improving the efficiency of water separation from a water/bitumen emulsion. Two types of motor oils (GS Caltex, Deluxe Gold V 7.5 W/30 and, Hyundai gear oil 85 W/140) were used as model oils in basic experiments to investigate the effects of a demulsifier on water/oil emulsion separation. Chemical demulsifiers showing good water separation performance were then used in asphalt emulsion and bitumen emulsion separation trials. Maleic anhydride and e-caprolactam were shown to be good oil soluble demulsifiers and 2-ethylhexyl acrylate and acrylic acid were effective as water soluble demulsifiers. Based on the results obtained in basic experiments, these four demulsifiers were used in further asphalt emulsion experiments. The oil soluble demulsifiers showed higher water separation efficiencies than the water soluble demulsifiers. To investigate the water separation efficiency using a combined chemical and electrical treatment method, the water/bitumen emulsion was separated with the electrical oil treatment apparatus after a chemical demulsifier had been added to it.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.609-614
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• 2010

In this study, emulsion polymerizations for synthesizing acrylic pressure-sensitive adhesive(PSA) were carried out using 2-ethylhexyl acrylate(2-EHA), n-butyl acrylate(n-BA), methyl metacrylate(MMA) as fundamental monomers and acrylic acid(AAc) as a functional monomer in the presence of anionic SLS (sodium lauryl sulfate). To obtain the optimized synthetic condition in the polymerization, we analyzed the polymerization variables such as the effect of surfactant concentration and hydrophilic lipophilic values(HLB). At the same time, the final adhesive properties were also analyzed by the function of the initiator concentration and buffer concentration. In the results, the most stable emulsion was obtained at the surfactant concentrations between 3 and 5 wt%. It was also determined the effect of HLB value of nonionic surfactant and the initiator concentrations on the gel content. Stable emulsion is obtained using the surfactant having HLB value of 12.3. The rate of emulsion polymerization was increased at the initiator concentration greater than 1 wt%, but the stability of the emulsion was decreased. Finally, the effect of the buffer concentrations on the pH and the conversion of the acrylic emulsion product were experimentally measured. At the sodium bicarbonate concentration above 0.4 wt%, the buffer infulence was apparent. The buffer effect was fully acceptable at the concentrations between 0.6 and 0.8 wt% regardless of the monomer composition.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.136-144
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• 1996

Polyacrylic super absorbent polymer(SAP) containing sorbitol was synthesized by inverse-suspension polymerization method. Sodium acrylate and acrylic acid were used as a monomer, ethylene glycol dimethacrylate(EGDMA) and glycerol polyglycidyl ether(GPGE) were used as a crosslinking agent, potassium persulfate(PPS) was used as an initiator, and cyclohexane was used as a solvent. Content of sorbitol was from 10mol% to 50mol% according to the mol ratio of acrylic acid monomer. The size distribution of the round shaped polymeric particle was $177{\sim}707{\mu}m$. Absorption amount of the polymer containing sorbitol was 785 to 1086 times of the polymer weight in distilled water, was 50 to 83 times in 0.9 % NaCl solution. Absorption and retention amount of the polymer were decreased with increasing the amount of sorbitol, but the polymer has an endothermic property which is +5 cal/g SAP.