• Polymer(Korea)
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• v.39 no.3
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• pp.468-474
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• 2015

Electrically conductive polymer nanocomposites were prepared by the inclusion of graphene-based nanofillers. Graphene oxide (GO) and reduced graphene oxide wrapped by poly(styrene sulfonate) (PSS-RGO) were used as nanofillers to make good dispersion with the aqueous dispersion of polystyrene (PS) particles. GO sheets were synthesized by the modified Hummers' method from graphite, and PSS-RGO sheets were prepared by the reduction of GO-dispersed PSS solution with hydrazine monohydrate. Morphology and properties of PS/GO and PS/PSS-RGO nanocomposites via latex technology were investigated. Both nanofillers showed well dispersed morphology in PS matrix. Rheological and electrical percolation thresholds were 0.28 and 0.51 wt% for GO, and 0.50 and 1.01 wt% for PSS-RGO respectively. It is speculated that PS/GO nanocomposites showed better conductivity than PS/PSS-RGO counterparts due to the partial recovery of GO by thermal reduction during molding.

• Polymer(Korea)
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• v.25 no.5
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• pp.617-624
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• 2001

The core-shell composite latexes were synthesized by stage emulsion polymerization of methyl methacrylate (MMA) and styrene (St) with ammonium persulfate after preparing monomer pre-emulsion in the presence of anionic surfactant. However, in preparation of core-shell composite latex, several unexpected results are observed, such as, particle coagulation, low degree of polymerization, and formation of new particles during shell polymerization. To solve the disadvantages, We study the effect of initiator concentrations, surfactant concentrations, and reaction temperature on the core-shell structure of polymethyl methacrylate/polystyrene and polystyrene/polymethyl methacrylate. Particle size and particle size distribution were measured using particle size analyzer, and the morphology of the core-shell composite latex was determined using transmission electron microscope. Glass temperature was also measured using differential scanning calorimeter. To identify the core-shell structure, pH of the two composite latex solutions were measured.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.163-172
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• 1996

Recently, the disposal of used vehicle tires is a big social problem because the amount of used vehicle tires has been increased with development of' automobile industry. Many researches have been made on the recycling of used vehicle tires in the various fields of industry as well as construction industry. When the crumb rubber made of vehicle tires is mixed in cement concrete and mortar, it is indicated that the adhesive strength of interface between the crumb rubber and cement hydrates is very low. The purpose of this study is to improve the fundamental properties by increasing of the adhesion strength of styrene-butadiene rubber(SF3R) latex coated crumb rubber in ; cement mortar. SBR-modified mortar using crumb rubber is also tested as the same method. From the test results, the cement mortar using SBR latex coated crumb rubber have a good fundamental properties compared with that using uncoated crumb rubber. The mechanical properties of SBR-modified mortar using crumb rubber with polymer-cement ratios of 10% are also improved.

• Safety and Health at Work
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• v.12 no.3
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• pp.396-402
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• 2021

Background: Styrene is one of the aromatic compounds used in acetonitrile-butadiene-styrene (ABS) producing petrochemicals, which has an impact on health of workers. Therefore, this study aimed to investigate the health risks of styrene emitted from the petrochemical industry in Iran. Methods: Air samples were collected based on NIOSH 1501 method. The samples were analyzed by the Varian-cp3800 gas chromatograph. Finally, risk levels of styrene's health effects on employees were assessed by the quantitative method of the U.S. Environmental Protection Agency (U.S. EPA) and the semiquantitative way by the Singapore Occupational Safety and Health Association. Results: Based on the results, the employees had the highest average exposure to styrene vapors (4.06 × 10^-1mg.(kg - day)^-1) in the polybutadiene latex (PBL) unit. Therefore, the most top predictors of cancer and non-cancer risk were 2.3×10^-4 and 7.26 × 10^-1, respectively. Given that the lowest average exposure (1.5 × 10^-2mg.(kg - day)^-1) was in the dryer unit, the prediction showed a moderate risk of cancer (0.8 × 10^-6) and non-cancer (2.3 × 10^-3) for the employees. The EPA method also predicted that there would be a definite cancer risk in 16% and a probable risk in 76% of exposures. However, according to the semiquantitative approach, the rate of risk was at the "low" level for all staff. The results showed that there was a significant difference (p < 0.05) between the units in exposure and health risk of styrene (p < 0.05). Conclusion: Given the high risk of styrene's health effects, appropriate control measures are required to reduce the exposure level.

• KSBB Journal
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• v.8 no.4
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• pp.320-327
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• 1993

Latex microspheres of styrene/acryl copolymer with acrylamide functional group were used for the stable covalent immobilization of an enzyme applicable for enzymatic synthesis of glycoside. The latex microspheres were coated with polyethyleneimine to establish structural and functional properties relevant to the covalent Immobilization with a high retention of activity. Polythyleneimine-coated microspheres satisfactorily immobilized the invertase for methyl fructoside synthesis, and model reaction were formed into alginate-enclosed microspheres biocatalyst. Using the alginate-enclosed microspheres biocatalyst, the yield of model glycoside was obtained as high as 52.2% at concentration of aqueous 30%(v/v) methanol and 0.291mo1/1 sucrose solution with 2U/ml of activity. The present study showed that the latex microspheres were successfully applied to enzymatic synthesis of glycoside.

• Elastomers and Composites
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• v.52 no.4
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• pp.272-279
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• 2017

The heterocoagulation of latex is a simple and useful method to fabricate various polymer nanocomposites in which a precise control of the colloid stability is essential. In this work, a multi-layered graphenes (MLGs)/poly(styrene-co-butyl acrylate) (P(S-co-BA)) nanocomposite having an excellent dispersion of MLGs was prepared via the sudden heating heterocoagulation process. The P(S-co-BA) component was obtained by emulsion polymerization. This process can effectively shorten the process and particles growth steps. The colloid stability of these dispersions was controlled by factors such as ionic charge, temperature, and reaction times. The influence of these factors on heterocoagulation was evaluated and the properties of the nanocomposites were investigated. The conductivity of the MLGs/P(S-co-BA) nanocomposites increased from -11.53 to -5.70 S/cm for an increase in MLG content from 0.01 to 5 wt%. Moreover, percolation threshold was observed in the case of 0.01 wt% MLGs.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.83-84
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• 2006

In aqueous phase, we directly prepared conducting and photoluminescent nano-structured particles by oxidation polymerization. Thiophene(PT) was initiated by $FeCl_{3}/H_{2}O_{2}$ (catalyst/oxidant) combination system. And, polydispersed core-shell poly(styrene/thiophene) and polyaniline(PANI)-coated multi core-shell polystyrene latex particles were successfully prepared by oxidative and radical polymerization. The resulting latex particles have fine improved luminescence and conductive efficiency and dispersion state due to the PT and PANI shell. Hyper functionalized nanoparticle would be expected to increase the processibility in various electrical and electro-optical fields.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.51-57
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• 1996

The purpose of this study is to improve the properties by increasing of the adhesion strength of styrene-butadiene rubber(SBR) latex coated powdered rubber in cement mortar. SBR-modified mortar using powdered rubber is also tested as the same method. From the test results, the cement mortar using SBR latex coated powdered rubber have a good mechanical properties compared with that using uncoated powdered rubber. The mechanical properties of SBR-modified mortar using powdered rubber with polymer-cement ratios of 10% are also improved.

• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.10-14
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• 2011

Emulsion polymerization was carried out using RMA like MMA, EMA, BMA and Styrene(St.) as monomer for core-shell latex preparation. It was synthesized at $80^{\circ}C$ in the presence of anionic surfactant SLS. FT-IR, TGA and DSC analysis are used to confirm synthesized core-shell emulsion latexes and to investigate the thermal characteristics of them. From analysis of TGA and DSC, the differences of the decomposition rate and the activation energy are not so large. It considers that the pendent group is not affect of the thermal characteristics and stability on core-shell latexes, which is synthesized with RMA and Styrene.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.84-92
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• 1996

The flexural and compressive strengths of polymer-modified mortars containing FRP wastes were investigated. The specimens of polymer-modified mortars containing FRP mortat were perpared by using styrene-butadiene rubber(SBR) latex, ethylene-vinyl acetate(EVA) emulsion and polyacrylic ester(PAE) emulsion with various FRP-sand ratios(10, 20, 30, 40, 50wt%). The compressive and flexural strengths of polymer-mokified mortars containing FRP wastes were decreased with an increase of FRP-sand ratio. But the compressive and flexural strengths of PAE polymer-modified mortar were more improved than OPC, whereas those of SBR and EVA polymer-modified mortars containing FRP wastes were decreased than OPC.