• Title, Summary, Keyword: polymer modifier

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Effect of Aminosiloxane Modifier on Chemorheological Properties of Ortho-cresol Novolac Epoxy (Ortho-cresol Novolac형 에폭시의 화학레올로지 특성에 미치는 아민 개질제의 영향)

  • 김윤진;안병길;김우년;서광석;김환건;윤초규
    • Polymer Korea
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    • v.26 no.1
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    • pp.88-97
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    • 2002
  • The effect of aminosiloxane modifier on the chemorheological properties of ortho-cresol novolac epoxy/phenol novelac/triphnylphosphine resin system was investigated aat different isothermal curing temperatures. By adding the aminosiloxane to the resin system, not only conversion rate and conversion were increased but also glass transition temperature was promoted. Critical conversion and gelation time obtained at the crossover point between storage and loss moduli were reduced and thus the viscosity was increased by the aminosiloxane. $C_1$ and $C_2$ in the WLF equation calculated from the glass transition temperature as a function of conversion and measured viscosity were found to vary with the curing temperature. By applying the change of glass transition temperature with conversion, $C_1$ and $C_2$ to WLF equation, it was possible to predict accurately the viscosity change with isothermal curing reaction.

Evaluation of Strengthening Capacity of Axial Member Using Admixture-Modified Mortar (혼화재 첨가 모르터를 이용한 압축부재의 보강성능 평가)

  • 박준명;양동석;박선규
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.417-422
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    • 2002
  • Strength and Durability of reinforced concrete exposed at deteriorated environment are decreased by cover spatting and corrosion of reinforcement. The purpose of this paper is to evaluate capacity of strengthening axial member using admixture-modified mortar. To investigate the capacity of strengthened axial member, behavior and strength of strengthening specimens were compared with a monolithic basic specimen. Admixture-modified mortar was prepared with silica fume, zeolite, polymer as cement modifier. From the result of this experiment, strengthening specimens using polymer-modified mortar have apparrent strengthening capacity because of good flexural strength and tensile strength.

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Durability of Polymers for Cement Modifier in Autoclave Cure (오토클래이브양생에 의한 시멘트 혼화용 폴리머의 내구성)

  • Joo, Myung-Ki;Lee, Youn-Su
    • Journal of the Korea Concrete Institute
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    • v.15 no.6
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    • pp.888-893
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    • 2003
  • The purpose of this study is to make clear the durability of the polymer films formed in the autoclaved polymer-modified mortars and concretes. The polymer films prepared with polymer dispersions such as a styrene-butadiene rubber (SBR) latex, a poly (ethylene-vinyl acetate)(EVA) emulsion and a polyacrylic ester (PAE) emulsion for polymeric admixtures are exposed to autoclaving at 18$0^{\circ}C$ in temperature and 1.01 MPa in vapor pressure, and subjected to tensile test and infrared spectroscopy. The durability of the polymer films is evaluated from the application of autoclaving to the polymer films under saturated Ca(OH)$_2$ solution immersion causes no degradation for SBR films and a significant degradation due to the saponification of the polymers for EVA and PAE films. Accordingly, in the application of autoclaving to polymer-modified mortars and concretes, it is suggested that SBR-modified mortars and concretes are hardly degraded but EVA- and PAE-modified mortars and concretes are markedly degraded by the saponification of the polymers.

The Study on Synthesis and Application of Polymer Dispersion for Cement Modifier (II) - The Waterproofing Effect of Cement Mortar using Acrylic Copolymer - (시멘트 혼화용 폴리머 합성과 그 응용에 관한 연구(II) - 아크릴공중합체를 이용한 시멘트 모르터의 방수성 -)

  • Kim, Hong-Dai;Kim, Young-Geun;Kim, Seung-Jin;Park, Hong-Soo
    • Applied Chemistry for Engineering
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    • v.7 no.4
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    • pp.679-690
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    • 1996
  • Acrylic copolymer was synthesized from 2-dimethylaminoethyl methacrylate and alkylmethacrylate containing long chain hydrocarbon group. To facilitate emulsification in water, acrylic copolymer was treated with acetic acid, and therefore acetated acrylic copolymer was produced. Acetated acrylic copolymer was perfectly emulsified in water and showed increased emulsion stability. Polymer as a cement dispersion agent(PDCM-PSD) was prepared by blending the newly synthesized acetates acrylic copolymer with sodium gluconate, oleic acid, and triethanolamine. The applicability of the blended polymer was examined, and it was found that the effects of dispersion and water-proof(0.3~0.5) were excellent.

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A Study on the Storage Stability of Waste Vinyl-Modified Asphalt (폐비닐로 개질된 아스팔트의 저장안정성에 관한 연구)

  • Kim, Kang-San;Hong, Young-Keun
    • Elastomers and Composites
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    • v.43 no.3
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    • pp.191-198
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    • 2008
  • It is said that polymer modified asphalt using polyethylene as modifier would show phase separation due to density difference and incompatibility between asphalt and polyethylene. In this study, to prevent coalescence of polyethylene in asphalt, we employed peroxides as phase separation inhibitor. On microscope, peroxides (dicumyl peroxide, lauroyl peroxide) with waste vinyl (comprising low density polyethylene) did not show phase separation, however, rheometer test showed phase separation at molecular level, i.e., polyethylene and asphalt are immiscible ultimately. Mechanical properties (tensile strength, Marshall stability, dynamic stability) showed waste vinyl-modified asphalts are highly resistant to plastic deformation and these properties are even better than those of Superphalt.

Phospholipid polymer can reduce cytotoxicity of poly (lactic acid) nanoparticles in a high-content screening assay

  • Kim, Hyung Il;Ishihara, Kazuhiko
    • Biomaterials and Biomechanics in Bioengineering
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    • v.1 no.2
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    • pp.95-104
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    • 2014
  • The objective of this study was to evaluate the cytotoxicity of poly (lactic acid) (PLA) nanoparticles. We used a water-soluble, amphiphilic phospholipid polymer, poly (2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB30W), as a stabilizer for the PLA nanoparticles. The PLA nanoparticles and PMB30W-modified PLA (PLA/PMB30W) nanoparticles were prepared by evaporating tetrahydrofuran (THF) from its aqueous solution. Precipitation of the polymers from the aqueous solution produced PLA and PLA/PMB30W nanoparticles with a size distribution of $0.4-0.5{\mu}m$. The partial coverage of PMB30W on the surface of the PLA/PMB30W nanoparticles was confirmed by X-ray photoelectron spectroscopy (XPS) and dynamic light-scattering (DLS). A high-content automated screening assay (240 random fields per group) revealed that the PLA nanoparticles induced apoptosis in a mouse macrophage-like cell line (apoptotic population: 73.9% in 0.8 mg PLA/mL), while the PLA/PMB30W nanoparticles remained relatively non-hazardous in vitro (apoptotic population: 13.8% in 0.8 mg PLA/mL). The reduction of the apoptotic population was attributed to the phosphorylcholine groups in the PMB30W bound to the surface of the nanoparticle. In conclusion, precipitation of PLA in THF aqueous solution enabled the preparation of PLA nanoparticles with similar shapes and size distribution but different surface characteristics. PMB30W was an effective stabilizer and surface modifier, which reduced the cytotoxicity of PLA nanoparticles by enabling their avoidance of the mononuclear phagocyte system.

Synthesis and Applications of Reactive Polymer Modifiers for Asphalt(1) (아스팔트용 반응성 고분자 개질제 합성 및 적용(1))

  • Hwang, Ki-Seob;Ahn, Won-Sool;Suh, Soong-Hyuck;Ha, Ki-Ryong
    • Polymer Korea
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    • v.31 no.1
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    • pp.68-73
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    • 2007
  • This study is on the synthesis of reactive polymer modifiers by emulsion polymerization to improve properties of asphalt for paving. Styrene, methyl methacrylate (MMA), isoprene and glycidyl methacrylate (GMA) which has epoxy ring to react with carboxyl group of asphaltene were used to synthesize polymer modifiers. Modifiers with various composition were tested miscibility with asphalt. Modifiers which showed good miscibility with asphalt were investigated by DSC for $T_g$. Existence of epoxy rings and their reaction with asphaltene wore investigated by FTIR. Molecular structures of synthesized modifiers were confirmed by $^1H-NMR$. The synthesized modifiers which showed good miscibility had their $Tg's$ in the range of $37.5{\sim}56.5^{\circ}C$ and had isoprene contents of 30 wt%. They showed good miscibility in the 1 and 2 wt% concentrations, but not in the 3 wt% concentration.

Morphology, Transparency, and Thermal Resistance of SAN Nanocomposites Containing Organically Modified Layered Double Hydroxides (유기변성 LDH를 사용한 SAN 나노컴포지트의 형태학, 투명성 및 내열성)

  • Kim, Seog-Jun
    • Polymer Korea
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    • v.36 no.3
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    • pp.287-294
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    • 2012
  • ZnAl-LDH(layered double hydroxide) (Zn:Al=2:1 mole ratio) modified with stearic acid (SA) or oleic acid (OA) was synthesized by a coprecipitation method and compounded to SAN polymer at various contents. All the SAN composites were manufactured by a co-rotating twin-screw extruder and subsequently injection molded into several specimen. Morphology, transparency, and thermal resistance of these composites were evaluated by TEM, XRD(X-ray diffractometry), UV-Vis spectrophotometry, and thermogravimetric analysis. SAN nanocomposites containing OA-$Zn_2Al$ LDH showed better optical transmittance than SAN nanocomposites containing SA-$Zn_2Al$ LDH. All the SAN nanocomposites containing OA-$Zn_2Al$ LDH or SA-$Zn_2Al$ LDH exhibited improvement of thermal resistance at second stage of thermal oxidation. These results were explained by the fact that the interaction between organic modifier and polymer performed an important role in the property improvement of polymer nanocomposites.

Toughness of Polyurethane-Modified Unsaturated Polyester Resin (폴리우레탄으로 개질한 불포화 폴리에스테르 수지의 강인성)

  • Hwang, Yeong-Geun;Min, Kyung-Eun;Choi, Gwan-Young;Kim, Woo-Sik;Lee, Dong-Ho;Park, Lee-Soon;Seo, Kwan-Ho;Kang, Inn-Kyu;Jun, Il-Ryun
    • Polymer Korea
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    • v.25 no.1
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    • pp.71-77
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    • 2001
  • Unsaturated polyester(UP) resin is one of the major thermosetting resins. It is very useful as the matrix resin of the composite material because of its low viscosity. The polymer resin, however, has several drawbacks; The volume shrinkage occurs during the crosslinking reaction of the UP resin with styrene monomer and the resulting polymer is weak to the alkali and also brittle. The mechanical properties of UP resin can be improved by blending various materials. In this study, polyurethane(PU) was used as a modifier in order to enhance the toughness of the UP resin. The goal of the research is to study the effect of the polyol molecular weight as a PU soft segment and the PU contents on the toughness of PU-modified UP resins. UP/PU polymer network may occur through the reaction between isocyanate group in the methyldiisocyanate(MDI) and hydroxyl group in the UP molecules. The maximum toughness value was shown at 2 wt% of the PU content. This effect results from the incorporation of the PU segment into the UP resin.

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Synthesis of Atactic Polypropylene-Polyacrylamide Graft Polymer and Adsorption on the Surface of Carbon Fiber (Atactic Polypropylene-Polyacrylamide 그라프트 중합체의 합성과 탄소섬유 표면에 대한 흡착)

  • 최호영;윤종선
    • Textile Science and Engineering
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    • v.30 no.2
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    • pp.150-161
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    • 1993
  • As a surface modifier, atactic polypropylene(APP)-g-polyacrylamide(PAAm) had been synthesized by inverse emulsion graft polymerization technique emulsifying the toluene solution of APP(Mw 8,000) containing tween #80(an emulsifier) and aqueous acrylamide(AAm) solution. The elects of various polymerization conditions on the AAm conversion, grafting efficiency, and % grafting had been investigated and the results were compared with those of the graft polymerizations of AAm onto isotactic polypropylene(IPP) (Mw 200,000) and high density polyethylene(HDPE) (Mw 20.000) by the same method. Those values were decreased with the increase of rpm. And the reducing phenomena for those values appeared at lower rpm and were more pronounced with the increasing rpm compared with those phenomena of the graftings onto IPP and HDPE. On the other hand, carbon fibers were treated with aqueous dispersion solution of water-dispersible graft polymer(WDGP) (isolated from gross polymers) under several concentrations. Temperatures treating times and pH values of solution. The effects of those conditions on the adsorption amount were investigated and compared with those in the adsorption of water-dispersible IPP-g-PAAm and HDPE-g-PAAm. The optimum adsorption appeared at lower treating temperature (4$0^{\circ}C$) than those(80~86$^{\circ}C$) for the graft polymers of IPP and HDPE.

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