• Polymer(Korea)
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• v.34 no.2
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• pp.89-96
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• 2010

Adhesive binders with core-shell structure of organic/organic pair were prepared by emulsion polymerization of acrylic monomers, such as methyl methacrylate(MMA), ethyl acrylate(EA), n-butyl acrylate(BA), and styrene(St). Ammonium persulfate (APS) was used as an water soluble initiator in the presence of an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS). Non-woven fabric and leather were impregnated with the adhesive binder. The surface of the impregnated fabric and leather were treated with plasma technique and then kinetics analysis and mechanical properties were measured. The conversions of the polymerization of core-shell binder (MMA/EA, MMA/BA) were greater than 90%. When the core-shell binder was prepared at equimolar conditions, the increasing effect of the core-shell binder on the state peel strength of the impregnated and plasma-treated non-woven/non-woven fabric has the order of MMA/St, EA/BA, BA/MMA, EA/St, and EA/MMA. When the core-shell binder was prepared at non-equimolar conditions, the increasing effect of the core-shell binder on the state peel strength of the non-woven fabric/leather has the order of MMA/BA, BA/EA, MMA/EA, St/MMA, and EA/St.

• Journal of the Korean Applied Science and Technology
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• v.22 no.2
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• pp.96-105
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• 2005

Core-shell polymers of methyl methacrylate-styrene system were prepared by sequential emulsion polymerization in the presence of sodium dodecyl benzene sulfonate(SDBS) as an emulsifier using ammonium persulfate(APS) in an initiator and the characteristics of these core-shell polymers were evaluated. Core-shell composite latex has the both properties of core and shell components in a particle, whereas polymer blends or copolymers show a combined physical properties of two homopolymers. This unique behavior of core-shell composite latex can be used in various industrial fields. However, in preparation of core-shell composite latex, several unexpected matters are observed, for examples, particle coagulation, low degree of polymerization, and formation of new particles during shell polymerization. To solve this matters, we study the effects of surfactant concentrations, initiator concentrations, and reaction temperature on the core-shell structure of PMMA-PSt and PSt-PMMA. Particle size and particles distribution were measured by using particle size analyzer, and the morphology of the core-shell composite latex was observed by using transmission electron microscope. Glass temperature was also measured by using differential scanning calorimeter. To identify the core-shell structure, pH of the composite latex solutions was measured.

• Nuclear Engineering and Technology
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• v.5 no.2
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• pp.103-114
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• 1973

Radiation grafting of acrylic acid and 4-vinylpyridine at room temperature has been studied by an impregnation method to improve the hygroscopic properties, the antistatic behavior and the dyeability of polyester fabric. Polyester fabric was impregnated with acrylic acid or aqueous emulsion of acrylic acid-4-vinylpyridine by immersion at 25$^{\circ}$or 7$0^{\circ}C$. The impregnated fabric was irradiated under nitrogen gas with ${\gamma}$-rays from Co-60. When acrylic acid grafted polyester fabric was treated with sodium carbonate, calcium acetate and potassium persulfate, tne rate of water absorption was increased and most parts of polyacrylic acid formed were extracted off from the fabric with 0.1% solution of sodium hydroxide at 10$0^{\circ}C$. In the case of the impregnation of a mixture of acrylic acid and 4-vinylpyridine the petcent of grafting has been shown to be proportional to the ratio of 4-VP/AA and radiation dost. Estimating by contact angle measurements of water on the various polymer surfaces, the antistatic behavior was decreased with the increase of grafting percent. The investigation of electron micrograph disclosed the existence of certain type of discontinuities in the acrylic acid grafted polyester fiber which was treated with various salts.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1076-1081
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• 2012

For the purpose of development of the latex suitable for latex modified concrete, experimental researches on the preparation of carboxylated styrene butadiene latex by the method of the two-step emulsion polymerization and application to concrete were performed. Sodium dodecylbenzene sulfonate and sodium salt of lauryl sulfonate were selected as anionic emulsifiers, and nonylphenoxy poly(ethyleneoxy) ethanols (n=10, 20, 40) as latex stabilizer. Potassium persulfate and sodium bisulfite were used as redox initiator, besides $Na_2HPO_4$ and $K_2CO_3$ as electrolytes. Polymerization recipe of latex suitable for latex modified concrete were suggested from the experimental researches on the effects of anionic emulsifiers and their concentration on the polymerization stability, and the effect of electrolytes concentration on the particle size of latex. Physical properties, such as slump, air contents, compressive and flexural strength, of latex prepared by suggested polymerization recipe were examined. The experimental results showed that latex modified concrete satisfied the quality standards in slump and air contents. Furthermore, it was turned out that the compressive and the flexural strength of latex modified concrete with 28 days curing time showed appreciably improvements.

• Elastomers and Composites
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• v.48 no.4
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• pp.294-299
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• 2013

Solution polymerization was conducted with water-soluble methacrylic acid (MAA) as a monomer and potassium persulfate (KPS) as an initiator at a selected temperature between $70^{\circ}C$ and $90^{\circ}C$. When the ratio between MAA and water was reduced or initiator concentration increased, molecular weights decreased. Molecular weights of poly(methacrylic acid) (PMAA) showed nearly no dependence on reaction temperature. The Weissenberg effect was observed in most polymerization reactions, while its effect weakened at $90^{\circ}C$. The polydispersity index was less than 1.5 in most of the reactions. An increase in the stirring speed produced PMAAs with increasing molecular weights. When the stirring speed reached 800 rpm, we retrieved a monodisperse PMAA with both the number and weight average molecular weights of 791,000 g/mol. The glass transition temperature was found to be $162^{\circ}C$.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.59-64
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• 2012

Polystyrene latex spheres (PLS) were prepared as artificial dusts by the emulsion polymerization with potassium persulfate (KPS) and sodium dodecyl sulfonate (SDS) as an initiator and a stabilizer, respectively. The reaction temperature and the concentration of the initiator and stabilizer were chosen as variables to control the PLS particle size. As temperature increased, the particle size decreased considerably. Furthermore, the PLS particle size and their size distributions can be controlled minutely by adjusting the concentrations of KPS and SDS. It is confirmed that the PLS prepared in this work is monodispersed with the coefficient of variance less than 7% and are in the range of 0.1~0.5 ${\mu}m$, which are good for using as artificial dusts.

• Polymer(Korea)
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• v.24 no.5
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• pp.629-637
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• 2000

Dispersion polymerization of acrylamide in the media of t-butyl alcoho1/$H_2O$ mixtures at 30~5$0^{\circ}C$ in the presence of hydroxypropyl cellulose and ammonium persulfate as steric stabilizer and initiator, respectively, was carried out. It was studied the effects of concentrations of initiator and steric stabilizer, amount of monomer, polymerization temperature, t-butyl alcohol/$H_2O$ ratio, concentration of crosslinker, purification of monomer and nitrogen purge on the particle size of the resulting acrylamide latices and molecular weight of the latex-poly(acrylamide). In this study, poly(acrylamide) latices of 0.1~0.5 ${\mu}{\textrm}{m}$ with 470000~2080000 in (equation omitted) were prepared and the resulting PAM latices were all dissolved in water in stantly.

• Membrane Journal
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• v.6 no.4
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• pp.258-264
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• 1996

Polyanilines were prepared by the oxidative polymerization in the presence of ammonium persulfate as an oxidant. After dehydration, a doping was carried out by mixing the polymer solution with dopants and immersing into aqueous dopant solutions. Using various riopants, the d-spacing of polyanilines can be controlled from $3.72{\AA}$ to $4.844{\AA}$. The d-spacing of polyanilines with polymeric or bulky dopants was larger than that of as-cast polyaniline. The characterization of the physical properties were confirmed by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), dielectric analyzer (DEA) etc. Annealed polyaniline membrane exhibited the oxygen permeability of 0.072 barrer and the oxygen selectivity to nitrogen was 6.87. For the gas separation of polyanilines with polymeric or bulky riopants, the permeability increased while the selectivity detereased. Permeability can be readily controlled by the use of bulky dopants.

• Elastomers and Composites
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• v.49 no.3
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• pp.232-238
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• 2014

Solution polymerization was conducted with water-soluble acrylic acid (AA) as a monomer and potassium persulfate (KPS) as an initiator at a selected temperature between $60^{\circ}C$ and $90^{\circ}C$ with water as a reaction medium. When the ratio between AA and water was reduced or initiator concentration increased, molecular weights decreased. An increase in the reaction temperature produced lower molecular weights. The polydispersity index was close to 1.5 in most of the reactions. An increase in the stirring speed up to 400 rpm led to a progressive increase in molecular weights. When the stirring speed reached 800 rpm, however, we found that both the number and weight average molecular weights decreased. The glass transition temperature was nearly independent of moelcular weights and determined to be between $113^{\circ}C$ and $116^{\circ}C$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.9-14
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• 2004

In this study, Si anisotropic etching characteristics of tetramethylammonium hydroxide (TMAH)/ ammonium persulfate(AP)/isopropyl alcohol(IPA) solutions were investigated to realize the optimum structure of a diaphragm for the piezoresistive pressure sensor application. Due to its low toxicity and its high compatibility with the CMOS processing, TMAH was used as Si anisotropic etchants. The variations of Si etch rate on the etching temperature, TMAH concentration, and etching time were obtained. With increasing the etching temperature and decreasing TMAH concentrations, the Si etch rate is increased while a significant non-unifonnity exists on the etched surface because of formation of hillocks on the (100) surface. The addition of IPA to TMAH solution leads to smoother etched surfaces but, makes the Si etch rate lower. However, with the addition of AP to TMAH solution, the Si etch rate is increased and an improvement in flatness on the etching front is observed. The Si etch rate is also maximized with increasing the number of addition of AP to TMAH solution per one hour. The Si square membranes of 20${\mu}{\textrm}{m}$ thickness and l00-400${\mu}{\textrm}{m}$ one-side length were fabricated successfully by applying optimum Si etching conditions of TMAH/AP solutions.