• Elastomers and Composites
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• v.33 no.4
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• pp.281-289
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• 1998

Tensile properties including Young's modulus and tear strength were measured for four different rubber compounds; natural rubber(NR), styrene-butadiene copolymer(SBR), ethylene-propylene diene monomer (EPDM), and brominated isobutylene-p-methyl-styrene copolymer(BIMS) as a function of temperature and degree of cure. To see the effect of over cure, a measurement was made of the tensile strength and swelling behavior of the over-cured rubber compounds. Young's modulus, E, was found to have linear dependency on the degree of cure for all rubber compounds. EPDM and BIMS showed the highest and lowest slopes, respectively. The slope of NR and SBR lay between EPDM and BIMS. Tear strength, Gc, decreased in the order of NR>BIMS>SBR>EPDM. As the cure time was extended the degree of cure of NR and SBR decreased, while that of BIMS increased. EPDM showed little change in the degree of cure.

• Korean Journal of Materials Research
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• v.29 no.7
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• pp.399-407
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• 2019

This research is carried out to analyze the effects of Styrene and PVP on the properties of silicone hydrogel lenses. Styrene group and PVP(Polyvinylpyrrolidone) are used as additives for a basic combination containing silicone monomer, TSMA(trimethylsilyl methacrylate) and DMA(n,n-dimethylacrylamide) added to the mix at ratios of 1~10 %. Silicone hydrogel lens is produced by cast-mold method. The polymerized lens sample is hydrated in a 0.9 % saline solution for 24 hours before its optical and physical characteristics are measured. Measurement of the physical characteristics of the produced material shows that the refractive index is 1.3682~1.4321, water content 77.11~45.73 %, visible light transmittance 95.14~88.20 %, and tensile strength 0.0652~0.3113 kgf. The results show a decrease of refractive index as the ratio of additives and water content decreases. The result of the stabilization test of polymerization show an increase of extractables along with increase of the ratio of additives, but the difference is not significant for all samples, so it can be judged that the stabilization of the polymer is maintained. Therefore, the additions of styrene and PVP should be taken into consideration for their effects on the physical properties of silicone hydrogel lens.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.69.5-69
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• 2002

1. Introduction 2. System Description 3. Hybrid Modeling of SM Reactor 4. Simulation Results 5. Optimization of Operating Condition 6. Conculsion

• Journal of Pharmaceutical Investigation
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• v.19 no.4
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• pp.173-178
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• 1989

Drug release rates from copolymer hydrogels were controlled by their hydrophilic-hydrophobic balances. As a model copolymer hydrogel, poly(acrylamide-co-styrene) was synthesized at different monomer composition. Release mechanisms of propranolol-HCI from the copolymer matrices were investisated. Swelling rates of the copolymer hydrogels retarded as their hydrophobicity increased. Swelling kinetics of the copolymer hydrogels regulated drug release rates via polymer relaxation controlled release mechanisms. Zero order drug release could thus be achieved within certain periods.

• Journal of the Korean Applied Science and Technology
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• v.27 no.1
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• pp.93-97
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• 2010

Silicone dioxide absorbed polyoxyethylene alkylether sulfate (EU-S75D) surfactant was prepared. The core-shell composite of inorganic/organic were polymerized by using styrene(St) as a shell monomer and potassium persulfate(KPS) as an initiator. We studied the effect of surfactants on the core-shell structure of silicone dioxide/styrene in the presence of an anionic surfactant lauryl sulfate(SLS). The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer(TGA) and morphology of latex by scanning electron microscope(SEM).

• Journal of the Korean Applied Science and Technology
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• v.25 no.3
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• pp.404-409
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• 2008

The core-shell composite particles of inorganic/organic were polymerized by using styrene(St) as a shell monomer and potassium persulfate (KPS) as an initiator. We studied the effect of core-shell structure of silicone dioxide/styrene in the presence of an anionic surfactant sodium lauryl sulfate (SLS) and polyoxyethylene alky lether sulfate (EU-S133D). We found that when $SiO_2$ core/PSt shell polymerization was prepared on the surface $SiO_2$ particle, to minimize the coagulation during the shell polymerization, the optimum conditions were at concentration of $2.56{\times}10^{-2}mole/L$ SLS. The structure of core-shell polymer was confirmed by measuring the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of core-shell polymer particles by transmission electron microscope (TEM).

• Journal of the Korean Chemical Society
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• v.14 no.4
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• pp.333-339
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• 1970

1) The copolymerzation of acrylamide $(M_1)$ with styrene $(M_1)$ was studied in absolute methanol solution at $50^{\circ}C$, using azobisisobutyronitrile as a initiator. The monomer reactivity ratios determined at $50^{\circ}C$ were as follows: $r_1=0.2,\;r_2=1.05$ and from these values, Q and e values for acrylamide were calculated as 0.37$(Q_1)$ and 0.45 $(e_1)$. 2) Overall activation energy of copolymer was calculated to 24.3K/cal mol, using the Arrhenius epuation. 3) Measurement of intrinsic viscosity and observation of physical properties were made on the copolymer.

• Polymer(Korea)
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• v.35 no.4
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• pp.314-319
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• 2011

The syndiotactic and atactic poly (2-N-carbazoylrnethyl) styrenes were obtained by a half-titanocene catalyst and a radical initiator for the investigation of photophysical properties, especially excimer formation. The atactic polymer exhibited only monomer emission, but the syndiotactic polymer showed both excimer emission and monomer emission resulting from the partial overlapping arrangement of carbazole pendants, The emission band of syndiotactic polymer was considerably dependent on solution concentration and temperature, however atactic polymer was independent because the excimer formation of syndiotactic helical conformation was more favorable than that of the random coil conformation of atactic polymer.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.444-446
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• 2011

Nanosized polystyrene (PS) particles with the narrow size distribution were synthesized from styrene monomer at the presence of the surfactant (polyvinylpyrrolidone, PVP), the solvent of 95 % alcohol, and the initiator of benzoyl peroxide (BPO). Since the emulsion polymerization method was applied, many factors could have effects on the size of PS particles during polymeric process. Aside from the concentration of monomer, surfactant and initiator, the factors such as the stirring speed and the ultrasonic radiation were mainly studied. By adjusting the radiating time, PS particles with their size of about 400 nm were synthesized.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.267-267
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• 2019

The purpose of this study is to understand the risk of chemical product, Styrene Monomer(SM), shipped in a vessel. SM is harmful chemical product which can make injury, explosion and/or fire in a vessel. The understand of SM risk is very important to protect seafarer's body and vessel safety. This research can be expected that the understanding of SM risk by a seafarer's to prevent accidents by SM explosion/fire. In this study we used event tree analysis method using chemical reaction cased by explosion. As a result, we founded various chemical reaction and visualization for explosion path.