• Journal of Adhesion and Interface
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• v.2 no.4
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• pp.1-9
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• 2001

Silicone sealants are composed of polymer, plasticizer, crosslinker, catalyst and filler. Types and compositions of components are effected on sealant performances. In recent, use of alkoxy type silicone sealant increased due to environmental advantage. In this study, we investigated effects of component types and ratios on one-part room temperature curable alkoxy type silicone sealant preparation and adhesion properties. Alkoxy type silicone sealants were prepared with various PDMS (polydimethylsiloxane) viscosities. In addition, the effect of plasticizer, crosslinkers, and catalyst on sealant obtained from by mixture of PDMS viscosities of 20000 and 80000 was investigated. Reaction temperature on change of mixing time was observed, and then proper crosslinking systems were found. Adhesion (properties) of silicone sealants were measured. In the sealants preparation, stable reaction was achieved by adjusting composition variance ratio in the sealant mixture temperature below $40^{\circ}C$. The adhesion properties of sealant differ from substrate composition. The order of adhesion strength was glass/glass > glass/aluminum > aluminum/aluminum system. The elongation of sealant was increased as polymer viscosity and plasticizer content increased. The strength was increased as crosslinker and plasticizer decreased, while catalyst increased.

• Membrane Journal
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• v.15 no.3
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• pp.206-212
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• 2005

Acid-resistant poly(vinyl alcohol) (PVA) membranes connected with ethylene and ether groups were prepared via a thermal crosslinking reaction by varying the ratio of PVA to ethylene glycol diglycidyl ether (EGDE). The crosslinked membranes were characterized using FT-IR and swelling tests, respectively. Pervaporation behaviors with the PVA membranes were investigated for aqueous TFEA (2,2,2-trifluoroethanol) as a function of EGDE content and operating temperature. The pervaporation properties far MA (methacrylic acid)/water mixture were also carried out with the optimized PVA membrane. The PVA membranes prepared with EGDE showed more excellent acid-resistance than those crosslinked with gluaraldehyde. The membranes showed high permeation fluxes of 0.1 and $0.3\;km^2h$ and high separation factors of 100 and 900 in the $96\;wt\%$ TFEA and MA aqueous fred mixtures at high temperature above $80^{\circ}C$, respectively. These confirmed theses membranes could be used in esterification membrane reactor process for the production of 2,2,2-trifluoroethylmetacrylate (TFEMA).

• Membrane Journal
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• v.11 no.3
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• pp.133-139
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• 2001

The hydorgen ions in PVA/SSA membranes were substituted with monovalent metal ions, $Li^{+}$, $Na^{+}$, $K^{+}$, divalent metal ion forms, $Mg^{2+}$, $Ca^{2+}$, $Ba^{2+}$, trivalent metal ion forms, $Al^{+}$. The effect of exchange with metal ions was investigated through the swelling measurement and pervaporative experiments for water-ethanol and water-methanol mixtures at various operating conditions. In addition, ESCA analysis was carried out to study the substitution of the metal ions in membranes. The swelling ratio decerased in the sequence of $Li^{+}$, $Na^{+}$, $K^{+}$ and this might be due to the 'salting-out` effect while the swelling ratios for divalnet and trivalent ion-substituted membranes were affected by the combined effect of salting-out, electrostatic crosslinking and extent of metal ion substitution. For the pervaporation performance, PVA/SSA-$H^{+}$membrane showed the lowest flux and highest separation factor for all aqueous ethanol solutions. The typical results of the flux, 59 g/$m^{2}$hr and the separation factor, 44 were obtained at $50^{\circ}C$ for 90% ethanol aqueous mixture. For water-methanol solutions, the PVA/SSA membranes substituted with monovalent PVA/SSA membranes substituted with divalent and tribalent metal ions, both `salting-out` and electrostatic effects affected the pervaporative results.

• Polymer(Korea)
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• v.38 no.1
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• pp.69-73
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• 2014

In this study, polysaccharide-poly(vinyl alcohol) (PVA) hydrogels were prepared by using ${\gamma}$-ray and evaluated for potential application as an anti-inflammation patch. Ulmus davidiana var. japonica (UD), one of polysaccharides has been particularly used as an oriental remedy for the treatment of inflammation and ulcers. PVA as a biocompatible polymer and glycerin as a moisturizer were blended with the UD, and its hydrogels were prepared by radiation crosslinking. Characterizations for UD hydrogels were performed by using cytotoxicity assay, antioxidant activity test, and physicochemical test such as gel fraction ratio, and swelling behavior. The results showed that these UD hydrogels had excellent physical properties, anti-inflammation activity, and non-cytotoxicity on the cells. Therefore, these polysaccharide based-UD hydrogels can be effectively used as an inflammation patch.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.561-568
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• 2021

In this study, in order to observe the change in the amount of Tire and Road Wear Particles and the ratio of tire components in it according to the tire wear resistance performance, carried out the evaluation by varying the vulcanization reaction design of the tire tread rubber. In addition, in order to improve the reliability of the evaluation of Tire and Road Wear Particles, the evaluation was performed indoor laboratory test equipment that simulates the condition on real driving to exclude various environmental influences including minerals, driver's habits, road surface, weather, tire structure and pattern designs. After the evaluation in closed space, it is estimated that the amount of collected Tire and Road Wear Particles is 84% compared to 100% of the tire and road wear loss weight, of which 96.4~97.7% was around the road and 2.3~3.6% was in the air. As a result of analy sis of the collected Tire and Road Wear particles, the tire component existed 63~75% in the Tire and Road Wear Particles depending on the wear resistance performance of the tire.

• Journal of Adhesion and Interface
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• v.23 no.2
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• pp.44-52
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• 2022

Epoxy resin has the disadvantage of being easily destroyed by instantaneous impact due to its high crosslinking density despite its high glass transition temperature (T_g) and excellent properties. To compensate for this, in this study, polyol was synthesized by ring opening polymerization of propylene glycol (PPG) diamine, Jeffamine D 2000 and propylene carbonate, and urethane modified epoxy was synthesized using this. The properties of the synthesized urethane modified epoxy were confirmed by FT-IR, H-NMR. To confirm the degree of improvement in impact resistance as an adhesive, a urethane modified epoxy adhesive was prepared by mixing a digylcidyl ether bisphenol A (DGEBA) with curing agent and curing accelerator. Properties test of urethane modified epoxy were shear strength, tensile strength and impact strength. As a result, excellent results were obtained in all test when the ratio of DGEBA : urethane modified epoxy was 8:2.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.595-604
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• 1992

Carbonate-type polyurethane resins containing anionic moieties were systhesized from NCO-terminated prepolymer method. Membranes were manufactured from the polymer solution and the separation of aqueous ethanol solution was investigated. To enhance the property of urethane resin, carbonate-type polyol(PTMCG) was used. ${\alpha}^{\prime},{\alpha}^{{\prime}{\prime}}$-dimethylolpropionic acid was used as a chain extender to increase the hydrophilicily of the urethane membrane. The ionization of the pendent carboxylic groups in urethane resin was carried out using trimthylamine. To confirm the formation of anionic groups in urethane resin, IR spectra of model compounds were compared with those of urethane resins. It was confirmed that the concentration of hard segment and hydrogen bond contributed to the property of the concentration of hard segment and hydrogen bond contributed to the property of urethane resin in which the mole ratio of chain extender and polyol was from 3:1 to urethane resin in which the mole ratio of chain extender and polyol was from 3:1 to 5:1. The carbonate-type polyurethane containing pendent carboxylic grop(PU) had Tg of around-$25^{\circ}C$ and Tm, $45^{\circ}C$ measured by DSC. Transition temperatures of one containing pendent anionic group(APU) prepared from the ionization of PU shifted to $8{\sim}10^{\circ}C$ lower temperature region than those of PU. Pervaporation membrane was prepared through the casting method. N, N-dimethylformamide (DMF) were used as a solvent and hexamethylene diisocyanate(HMDl) as a crosslinking agent. Swelling degree increased with ethanol concentration in mixure and the control of the swelling degree of the membrane could be achieved by crossliking. The results of pervaporation were as follows : separation factor, 2.3~9.8 ; flux, $27{\sim}79.5g/m^2hr$. Pervaporation separation capacity could be enhanced by reducing the molecular weight of polyol from 2,000 to 1,000.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.636-642
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• 2013

In order to overcome drawbacks (i.e., filtration and recovery) of conventional powder type photocatalysts, nano-ZnO/Laponite/PVA (ZLP) photocatalyzed adsorption balls were developed by using in situ mixing of nanoscale ZnO as a photocatalyst, and Laponite as both adsorbent and supporting media in deionized water, followed by the poly vinyl alcohol polymerization with boric acid. The optimum mixing ratio of nano-ZnO:Laponite:PVA:deionized water was found to be 3:1:1:16 (by weight), and the mesh and film produced by PVA polymerization with boric acid might inhibit both swelling of Laponite and detachment of nanoscale ZnO from ZLP balls. Drying ZLP balls with microwave (600 watt) was found to produce ZLP balls with stable structure in water, and various sizes (55~500 ${\mu}m$) of pore were found to be distributed based on SEM and TEM results. In the initial period of reaction (i. e., 40 min), adsorption through ionic interaction between methylene blue and Laponite was the main removal mechanism. After the saturation of methylene blue to available adsorption sites for Laponite, the photocatalytic degradation of methylene blue occurred. The effective removal of methylene blue was attributed to adsorption and photocatalytic degradation. Based on the results from this study, synthesized ZLP photocatalyzed adsorption balls were expected to remove recalcitrant organic compounds effectively through both adsorption and photocatalytic degradation, and the risks of environmental receptors caused by detachment of nanoscale photocatalysts can be reduced.