• Polymer Science and Technology
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• v.18 no.1
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• pp.8-19
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• 2007

• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.235-241
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• 2013

In this study, a mortar was produced using re-dispersible polymer powders that addresses the defects of aqueous polymer and improves the durability of cement mortar. Also, an attempt was made to examine the properties of polymer modified mortars using re-dispersible polymer powders by strength and durability tests between ordinary Portland cement mortars and polymer modified mortars mixed with aqueous dispersion. The test showed that strength and durability are improved considerably compared with ordinary Portland cement mortar, and the performance of aqueous polymer cement mortar was considerably improved. Accordingly, it is expected that high-quality prepackaged polymer modified mortars can be produced using re-dispersible polymer powders.

• Journal of the Korea Institute of Building Construction
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• v.3 no.4
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• pp.103-109
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• 2003

Reinforced concrete structures under sever conditions such as marine structures, bridges and structural constructed with aggregated(dredged front sea). can be deteriorated from corrosion of the reinforcing bars. The purpose of this study is to evaluate the corrosion reflectance of coated steel using polymer dispersion and polymer cement slurry. Polymer dispersion and polymer cement slurry with various polymer types were coated to the surface of bars and steel plate, and tested for accelerated corrosion tests. Tests include adhesion in tension, bending test, chloride ion spray, penetration of NaCl 10％ solution and carbonation. From the test results, the corrosive resistance of steel is considerably improved by using polymer dispersion and polymer cement flurry at surface of steel. The difference of the corrosive resistance is hardly recognized according to types of polymer dispersion. The coated steel using polymer dispersion and polymer foment slurry will be improved to a great extent compared to those of plain steel when increasing content of chloride ion in cement concrete.

• The Journal of Korea Robotics Society
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• v.16 no.1
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• pp.41-48
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• 2021

In this paper, we review papers which report to the all solid-state electroactive polymer-based tunable lens. Since electroactive polymer-based tunable lenses change their focal length by responding to electric stimuli, it can be minimized the size and weight of optical modules. Thus, it has been received attention in the robot, mobile device and display industry. The all solid-state electroactive polymer-based tunable lenses can be classified into two categories depending on the classification of materials: ionic electroactive polymer-based lenses and non-ionic electroactive polymer-based lenses. Most of the ionic electroactive polymer-based tunable lenses are fabricated with ionic polymer-metal composite. So, the ionic electroactive polymer-based tunable lenses can be operated under low electric voltage. But small force, slow recovery time and environmental limitation for operation has been pointed to the disadvantage of the lenses. The non-ionic electroactive polymer-based tunable lenses are classified again into two categories: dielectric polymer-based tunable lenses and polyvinylchloride gel-based tunable lenses. The advantage of the dielectric polymer-based tunable lenses is fast response to electric stimuli. But the essential flexible electrodes degrade performance of the lens. Polyvinylchloride gel-based tunable lens has reported impressive performance without flexible electrodes.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.409-416
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• 2003

The effects of polymer-cement ratio, antifoamer content and shrinkage-reducing agent content on the air content, setting time, drying shrinkage and strength of polymer-modified mortars using redispersible polymer powder are examined. As a result, the air content of the polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and antifoamer content. Regardless of the antifoamer content, the setting time of the polymer-modified mortars using redispersible polymer powder tend to delayed with increasing polymer-cement ratio. Irrespective of the antifoamer content, the drying shrinkage of the polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and shrinkage-reducing agent content. Regardless of the antifoamer content, the flexural and tensile strengths of the ultrarapid-hardening polymer-modified mortars using redispersible polymer powder tend to increase with increasing polymer-cement ratio, and tend to decrease with increasing shrinkage-reducing agent content. However, the compressive strength of the ultrarapid-hardening polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and shrinkage-reducing agent content.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.610-613
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• 2009

New rod-disc liquid crystal (LC) molecule RD12 (12 is the number of carbon atoms between the rod and disc mesogenic liquid crystals) was synthesized via the chemical attachment of six cyanobiphenly calamitic mesogens linked to the triphenyl discotic mesogen with six alkyl chain linkage. Aligning characteristics associated with homogenous alignment is investigated at first and then field-dependent molecular reorientation under a vertical electric field is studied. Interestingly, they show abnormal slow molecular transition from initiate state (no electric field condition) to certain voltage. In this condition, we observe the molecular competition during reorientation. However, once a tilting direction of disk molecules are defined, the frustration is not observed anymore. The origin of this phenomenon is explained with a suggested model for the first time.

• Polymer(Korea)
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• v.32 no.6
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• pp.555-560
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• 2008

Polymer-modified mortars have been largely used as paving materials, flooring, waterproofing material, adhesives, anticorrosive linings, deck coverings, and other various materials. The various types and properties of the mixed polymer largely affect the characteristics of polymer-modified mortar that has been mixed with polymer latexes. Consequently, its application purposes are varied according to these properties. This paper investigates the typical properties of polymer-modified mortars that contain styrene and butyl acrylate latexes and styrene butadiene rubber. They are then tested to obtain air contents, water-cement ratios, flexural and compressive strengths, water absorption, and chloride-ion penetration. From the test results, the superior flexural strength of polymer-modified mortars is obtained at a S/BA-2 and a polymer-cement ratio of 20%. And, the water absorption and chloride ion penetration depth are greatly affected by the polymer-cement ratio rather than the types of polymer. In the polymer-modified mortar and concrete structures, aggregates are bound by such a co-matrix phase, resulting in the superior properties of polymer-modified mortar and concrete compared to conventional mortar and concrete.

• Polymer Science and Technology
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• v.16 no.5
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• pp.599-612
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• 2005

• Macromolecular Research
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• v.17 no.5
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• pp.361-364
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• 2009

• Journal of Adhesion and Interface
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• v.4 no.2
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• pp.30-36
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• 2003