• Title/Summary/Keyword: nanofiller

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Comparison of the Properties of Poly(lactic acid) Nanocomposites with Various Fillers: Organoclay, Functionalized Graphene, or Organoclay/Functionalized Graphene Complex (유기화 점토, 작용기화 그래핀 및 유기화 점토/작용기화 그래핀 복합체 등의 필러를 사용한 Poly(lactic acid) 나노 복합체의 물성 비교)

  • Kwon, Kidae;Chang, Jin-Hae
    • Polymer(Korea)
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    • v.38 no.2
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    • pp.232-239
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    • 2014
  • Poly(lactic acid)(PLA) nanocomposites containing various nanofillers were synthesized using the solution intercalation method. Organically modified bentonite clay (NSE), octadecylamine-graphene oxide (ODA-GO), and an NSE/ODA-GO complex were utilized as nanofillers in the fabrication of PLA hybrid films. PLA hybrid films with varying nanofiller contents in the range of 0-10 wt% were examined and compared in terms of their thermomechanical properties, morphologies, and oxygen permeabilities. Transmission electron microscopy (TEM) confirmed that most of the NSE and ODA-GO nanofillers were dispersed homogeneously throughout the PLA matrix on the nanoscale, although some agglomerate NSE/ODA-GO complex particles were also formed. Among the three nanofillers for PLA hybrid films, the NSE/ODA-GO complex showed the best improvement in film thermal stability. In contrast, NSE and ODA-GO exhibited the best improvement in tensile mechanical properties and oxygen barrier properties of the PLA hybrid films, respectively.

Preparation and Mechanical Properties of Nanocomposite of Cellulose Diacetate/Montmorillonite (셀룰로오스 디아세테이트/몬모릴로나이트 나노복합체의 제조 및 기계적 물성)

  • 조미숙;최성헌;남재도;이영관
    • Polymer(Korea)
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    • v.28 no.6
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    • pp.551-555
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    • 2004
  • Cellulose diacetate (CDA) nanocomposite films were prepared by using various plasticizer and montmorillonite nanofiller in methylene chloride/ethanol (9:1 w/w) mixed solution. The thermal property (T$_{g}$) of prepared CDA films was observed by DSC and T$_{g}$ of the films was decreased with the increase in the plasticizer content. The degree of dispersion of MMT in the CDA film was observed by XRD and mechanical property of CDA film was measured by tensile strength and Young's modulus. When the plasticizer was added into the CDA film upto 30 wt%, the Young's modulus of film was decreased from 1930 MPa to 1131 MPa but was increased from 1731 MPa to 2272 MPa when the MMT was added into the film upto 7 wt%. The mechanical properties of CDA films were decreased by addition of plasticizer but strengthened by the incorporation of MMT.

Effect Of Silica Concentration and Crosslinking Agent on Adhesion Properties and Thermal Stability Of UV Cured 2-EHA/AA PSAs (자외선 경화형 2-EHA/AA 점착제의 점착 물성 및 열 안정성에 미치는 실리카 함량 및 경화제 효과)

  • Kim, Ho-Gyum
    • Journal of Adhesion and Interface
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    • v.16 no.2
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    • pp.55-62
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    • 2015
  • It was investigated that the effect of surface modification and concentration of fumed silica on the adhesion properties and thermal stability of 2-EHA/AA pressure sensitive adhesive (PSAs) prepared by UV irradiation. The influence of repeating units of crosslinking agent on PSAs were also studied. From SEM analysis, PSAs synthesized with surface modified silica had finer dispersion of silica particles in polymer matrix due to the interfacial interaction. Results of the study showed that increase in tack and peel strength when under 0.3 wt% of silane treated silica were added in the reaction mixture. The addition of PEGDMA for crosslinking agent offers positive effect on adhesion properties in comparison with PSAs using EGDMA for crosslinker, which may be attributed to high mobility of ethylene oxide repeating units in PEGDMA. From the thermal degradation residue of PSAs, it was revealed that thermal stability was improved with silica addition due to the strong interfacial bonding between silane modified silica and polymer matrix, which may act as a thermal barriers into 2-EHA/AA PSAs.

Preparation, Morphology and Electrical Conductivity of Polystyrene/Polydopamine- Carbon Nanotube Microcellular Foams via High Internal Phase Emulsion Polymerization (고내상 에멀젼 중합에 의한 폴리스티렌/폴리도파민-탄소나노튜브 미세기공 발포체의 제조, 모폴로지 및 전기 전도도)

  • Kim, Haseung;Na, Hyo Yeol;Lee, Jong Heon;Lee, Seong Jae
    • Polymer(Korea)
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    • v.39 no.2
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    • pp.293-299
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    • 2015
  • Conductive microcellular foams consisted of polystrene (PS) and polydopamine-coated carbon nanotube (PDA-CNT) were prepared via high internal phase emulsion (HIPE) polymerization and their morphology and electrical conductivity were investigated. CNT as a conductive nanofiller was modified to PDA-CNT by coating with hydrophilic PDA on the surface of CNT to increase aqueous phase dispersion and emulsion stability. It was possible to prepare the HIPEs having higher PDA-CNT content and the resultant foams having improved conductivity due to its good dispersion. The foams showed the morphology of interconnected cell structure. As PDA-CNT content increased, yield stress and storage modulus increased and cell size reduced. The PDA-CNT content showing electrical percolation threshold was ca. 0.58 wt% and the conductivity at PDA-CNT content of 5 wt% was increased to $10^{-3}S/m$.

Elastomer Nanocomposites(I) (엘라스토머 나노복합체(I))

  • Bang, Dae-Suk;Kye, Hyoung-San;Cho, Ur-Ryong;Min, Byung-Gak;Shin, Kyung-Chul
    • Elastomers and Composites
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    • v.44 no.1
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    • pp.22-33
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    • 2009
  • Recently, elastomer-nanocomposites reinforced with low volume fraction of nanofillers have attracted great interest due to their fascinating properties. The incorporation of nanofillers, such as, layered silicate clays, carbon nanotubes, nanofibers, calcium carbonate, metal oxides or silica nanoparticles into elastomers improves significantly their mechanical, thermal, dynamic mechanical, barrier properties, flame retardancy, etc. The properties of nanocomposites depend greatly on the chemistry of polymer matrices, nature of nanofillers, and the method in which they are prepared. The uniform dispersion of nanofillers in elastomer matrices is a general prerequisite for achieving desired mechanical and physical characteristics. In this paper, current developments in the field of elastomer nanocomposites reinforced with layered silicates, silica, carbon nanotubes, nanofibers and various other nanoparticles have been addressed.

The influence of nanofillers on the properties of ethanol-solvated and non-solvated dental adhesives

  • da Cruz, Leonardo Bairrada Tavares;Oliveira, Marcelo Tavares;Saraceni, Cintia Helena Coury;Lima, Adriano Fonseca
    • Restorative Dentistry and Endodontics
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    • v.44 no.3
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    • pp.28.1-28.10
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    • 2019
  • Objectives: The aim of this study was to evaluate the influence of different concentrations of nanofillers on the chemical and physical properties of ethanol-solvated and non-solvated dental adhesives. Materials and Methods: Eight experimental adhesives were prepared with different nanofiller concentrations (0, 1, 2, and 4 wt%) and 2 solvent concentrations (0% and 10% ethanol). Several properties of the experimental adhesives were evaluated, such as water sorption and solubility (n = 5, 20 seconds light activation), real-time degree of conversion (DC; n = 3, 20 and 40 seconds light activation), and stability of cohesive strength at 6 months (CS; n = 20, 20 seconds light activation) using the microtensile test. A light-emitting diode (Bluephase 20i, Ivoclar Vivadent) with an average light emittance of $1,200mW/cm^2$ was used. Results: The presence of solvent reduced the DC after 20 seconds of curing, but increased the final DC, water sorption, and solubility of the adhesives. Storage in water reduced the strength of the adhesives. The addition of 1 wt% and 2 wt% nanofillers increased the polymerization rate of the adhesives. Conclusions: The presence of nanofillers and ethanol improved the final DC, although the DC of the solvated adhesives at 20 seconds was lower than that of the non-solvated adhesives. The presence of ethanol reduced the strength of the adhesives and increased their water sorption and solubility. However, nanofillers did not affect the water sorption and strength of the tested adhesives.

Synergistic Effect of Sulfonated Poly(Ether Ether Ketone)/Strontium Zirconate Perovskite Nanofiber-Based Novel Electrospun Composite Membranes for Fuel Cell Applications (연료전지용 술폰화된 폴리(이써 이써 케톤)/스트론튬 지르코네이트 페로브스카이트 나노섬유 기반 신규 전기방사 복합막의 시너지 효과)

  • SELVAKUMAR, KANAKARAJ;KIM, AE RHAN;YOO, DONG JIN
    • Transactions of the Korean hydrogen and new energy society
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    • v.33 no.2
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    • pp.164-175
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    • 2022
  • In this work, sulfonated poly (ether ether ketone) (SPEEK) composite membranes including strontium zirconate (SrZrO3) were fabricated by the electrospinning method. Fourier-transform infrared spectroscopic analysis and X-ray diffraction analysis were used to identify the chemical structure and the crystallinity of SrZrO3 and electrospun composite membranes. The thermal stability of the pure SPEEK and SPEEK/SrZrO3 electrospun composite membranes were investigated by using thermogravimetric analysis. The physicochemical properties and proton conductivity were enhanced with the addition of different weight ratio of SrZrO3 nanofiller (2, 4 and 6 wt%) in SPEEK polymer. The optimized SPEEK/SrZrO3-4 electrospun membrane containing 4 wt% of SrZrO3 showed a high proton conductivity compared to other electrospun SPEEK/SrZrO3 composite membranes. The results indicate that electrospun composite membranes incorporating these perovskite nanofillers should be explored as potential candidates for use in proton exchange membrane fuel cells.

COMPARISON OF POLYMERIZATION SHRINKAGE AND STRAIN STRESS OF SEVERAL COMPOSITE RESINS USING STRAIN GUAGE (스트레인 게이지를 이용한 수종의 복합레진의 중합수축 및 수축응력의 비교)

  • Kim, Young-Kwang;Yoo, Seung-Hoon;Kim, Jong-Soo
    • Journal of the korean academy of Pediatric Dentistry
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    • v.31 no.3
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    • pp.516-526
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    • 2004
  • Polymerization shrinkage of photoinitiation type composite resin cause several clinical problems. The purpose of this study was to evaluate the shrinkage strain stress, linear polymerization shrinkage, compressive strength and microhardness of recently developed composite resins. The composite resins were divided into four groups according to the contents of matrix and filler type. Group I : $Denfil^{TM}$(Vericom, Korea) with conventional matrix, Group II : $Charmfil^{(R)}$(Dentkist, Korea) with microfiller and nanofller mixture, Group III : $Filtek^{TM}$ Z250(3M-ESPE, USA) TEGDMA replaced by UDMA and Bis-EMA(6) in the matrix, and Group IV : $Filtek^{TM}$ Supreme(3M-ESPE, USA) using pure nanofiller. Preparation of acrylic molds were followed by filling and curing with light gun. Strain gauges were attached to each sample and the leads were connected to a strainmeter. With strainmeter shrinkage strain stress and linear polymerization shrinkage was measured for 10 minutes. The data detected at 1 minute and 10 minutes were analysed statistically with ONE-way ANOVA test. To evaluate the mechanical properties of tested materials, compressive hardness test and microhardness test were also rendered. The results can be summarized as follows : 1. Filling materials in acrylic molds showed initial temporary expansion in the early phase of polymerization. This was followed by contraction with the rapid increase in strain stress during the first 1 minute and gradually decreased during post-gel shrinkage phase. After 1 minute, there's no statistical differences of strain stress between groups. The highest strain stress was found in group IV and followed by group III, I, II at 10 minutes-measurement(p>.05). In regression analysis of strain stress, group III showed minimal inclination and followed by group II, I, IV during 1 minute. 2. In linear polymerization shrinkage test, the composite resins in every group showed initial increase of shrinkage velocity during the first 1 minute, followed by gradually decrease of shrinkage velocity. After 1 minute, group IV and group III showed statistical difference(p<.05). After 10 minutes, there were statistical differences between group IV and group I, III(p<.05) and between group II and group III(p<.05). In regression analysis of linear polymerization shrinkage, group II showed minimal inclination and followed by group IV, III, I during 1 minute. 3. In compressive strength test, group III showed the highest strength and followed by group II, IV, I. There were statistical differences between group III and group IV, I(p<.05). 4. In microhardness test, upper surfaces showed higher value than lower surfaces in every group(p<.05).

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Preparation of Bio-Chemical Sensor Electrodes by Using Electrical Impedance Properties of Carbon Nanotube Based Bulk Materials (탄소나노튜브 기반 벌크 소재의 전기적 임피던스 특성을 이용한 생화학 센서용 전극 개발 연구)

  • So, Dae-Sup;Huh, Hoon;Kim, Hee-Jin;Lee, Hai-Won;Kang, In-Pil
    • Applied Chemistry for Engineering
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    • v.21 no.5
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    • pp.495-499
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    • 2010
  • To develop chemical and biosensors, this paper studies sensing characteristics of bulk carbon nanotube (CNT) electrodes by means of their electrical impedance properties due to their large surface area and excellence chemical absorptivity. The sensors were fabricated in the form of film and nano web style by using composite process for mass production. The bulk composite electrodes were fabricated with singlewall and multi-wall carbon nanotubes based on host polymers such as Nafion and PAN, using a solution-casting and an electrospinning technique. The resistance and the capacitance of electrodes were measured with LCR meter under the various amounts of buffer solution to study the electrical impedance change properties of them. On the experimental of sensor electrode, impedance characteristics of the composite electrode are affected by its host polymer and nanofiller and its sensing response showed saturated result after applying some amounts of buffer solution for test chemical. Especially, the capacitance values showed drastic changes while the resistance values only changed within few percent range. It is deduced that the ions in the solution penetrated and diffused into the electrodes surface changed the electrical properties of the electrodes much like a doping effect.

Comparison of microleakage after load cycling for nanofilled composite resin fillings with or without flowable resin lining (Nanofilled 복합레진으로 와동 충전 시 flowable 레진 사용 유무에 따른 피로시험 후의 미세 변연 누출 비교)

  • Han, Sun-Deok;Kim, Won;Choi, Ji-Young;Oh, Nam-Sik;Lee, Myung-Hyun
    • The Journal of Korean Academy of Prosthodontics
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    • v.47 no.3
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    • pp.342-347
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    • 2009
  • Statement of problem: when using resin for class II restoration, micoleakage by instrumentation can be regarded as the primary negative characteristic. A review of the available literature suggests that using flowable resin as liner to decreased microleakage. Purpose: The aim of this study was to determine the influence of the nanofilled flowable resin lining on marginal microleakage after load cycling in class II composite restoration fillings using nanofiller resin. Material and methods: 24 extracted premolars were prepared with class II cavity. F group was restored the nanofilled resin with the nanofilled flowable resin as liner. NF group was restored the nanofilled resin only. After restoration, an experiment was performed on 2 groups using a 300N load at 104, 105 and 106 cycles. Prior to and before each load cycling, it was gauged length on total marginal microleakage, axial marginal microleakage and buccal, gingival, lingual marginal microleakage. Data were analyzed with the Mann-Whitney test & Kruskal-Wallis test. Results: There were statistically significant differences between 2 groups and between individual groups. (P <.05) The result showed less microleakage in teeth restored by the nanofilled resin, which was lined by the nanofilled flowable resin. Conclusion: There was significant reduction in microleakage when the nanofilled flowable resin lining was placed underneath the nanofilled resin in class II composite restoration fillings.