• Title, Summary, Keyword: silica dispersion

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Correlation Research of Dispersion Factors on the Silica Sol Prepared from Fumed Silica (흄드실리카로부터 제조된 실리카졸의 분산인자 상관성 연구)

  • Park, Min-Gyeong;Kim, Hun;Lim, Hyung Mi;Choi, Jinsub;Kim, Dae Sung
    • Korean Journal of Materials Research
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    • v.26 no.3
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    • pp.136-142
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    • 2016
  • To study the dispersion factors of silica sol prepared from fumed silica powder, we prepared silica sol under an aqueous system using a batch type bead mill. The dispersion properties of silica sol have a close relationship to dispersion factors such as pH, milling time and speed, the size and amount of zirconia beads, the solid content of fumed silica, and the shape and diameter of the milling impellers. Especially, the silica particles in silica sol were found to show dispersion stability on a pH value above 7, due to the electrostatic repulsion between the particles having a high zeta potential value. The shape and diameter of the impellers installed in the bead mill for the dispersion of fumed silica was very important in reducing the particle size of the aggregated silica. The median particle size ($D_{50}$) of silica sol obtained after milling was also optimized according to the variation of the size and amount of the zirconia beads that were used as the grinding medium, and according to the solid content of fumed silica. The dispersion properties of silica sol were investigated using zeta potential, turbiscan, particle size analyzer, and transmission electron microscopy.

Effects of Coupling and Dispersion Agents on the Properties of Styrene-Butadiene Rubber/Butadiene Rubber Compounds Reinforced with Different Silica Contents

  • Yang, Jae-Kyoung;Park, Wonhyeong;Ryu, Changseok;Kim, Sun Jung;Kim, Doil;Kim, Jong-Ho;Seo, Gon
    • Elastomers and Composites
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    • v.53 no.3
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    • pp.109-123
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    • 2018
  • The effect of the silica content on the state and properties of silica-filled styrene-butadiene rubber/butadiene rubber (SBR/BR) compounds containing coupling and dispersion agents was evaluated by varying the content of silica from 50 to 120 phr. Bis-[(triethoxysilyl)propyl] tetrasulfide (TESPT) and zinc 2-ethylhexanoate (ZEH) were used as the coupling and dispersion agents, respectively. The maximum silica content in the pristine material was 80 phr, which increased to 120 phr upon the addition of TESPT and ZEH. The incorporation of TESPT considerably improved most of the rubber properties due to its coupling action and the suppression of silica flocculation, while further addition of ZEH resulted in additional improvements. The properties of the rubber compounds with different silica contents can be fully explained either by an enhancement of the rubber-silica interactions or by their deterioration due to an excessive amount of silica aggregates.

Influence of Nano Silica Dispersant on Hydration Properties of Cementitious Materials (시멘트의 수화특성에 대한 유·무기 복합 나노실리카의 영향)

  • Kang, Hyun-Ju;Song, Myong-Shin;Park, Jong-Hun;Song, Su-Jae
    • Journal of the Korean Ceramic Society
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    • v.48 no.6
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    • pp.510-515
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    • 2011
  • In this study, as a material used to replace silica fumes for high strength concrete, nano-silica compound with organic functional group for dispersion and with inorganic silica group that can cause a pozzolan reaction is synthesized, These nano silica compound is divided into IC, which is nano size $SiO_2$ with irregularly combined hydroxyl group and carboxyl group, and RC, which is nano size $SiO_2$ with regularly combined hydroxyl group and carboxyl group. The effects of these nano silica compound on the hydration of cement are reviewed. As a result, all of synthesized nano-silica compounds have excellent dispersion on the cement flow, we think that dispersion property is the effect of air entraining by synthesized nano-silica compounds. The result of the microstructure observation showed that the particle size of the synthesized nano-silica is smaller than silica fume and spread evenly among the cement particles. In initial The phenomenon of strength decreasing occurred due to delayed hydration reaction by the synthesized nano-silica with carboxyl(-COOH) and hydroxyl(-OH) functional group.

Fabrication of Silica-Containing Breathable Waterproof Polyurethane Dispersion Film (Silica를 함유하는 Polyurethane dispersion 투습방수 Film의 제조)

  • Shin, Hyun-Ki;Huh, Man-Woo;Yoon, Nam-Sik
    • Textile Coloration and Finishing
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    • v.27 no.2
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    • pp.126-131
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    • 2015
  • Silica-polyurethane hybrid breathable films were prepared and their breathabilities were assessed. Appropriately aggregated silica was prepared through sol-gel reaction of water glass and its particle size ranged 360~500nm. The polyurethane dispersion was prepared by the reaction of isophorone diisocyanate(IPDI) as diisocyanate and polytetramethylene glycol(PTMG) and dimethylol propionic acid(DMPA) as polyol, particle size ranging 30~120nm. The reaction between isocyanate and hydroxyl group to form urethane bonding was checked by the intensity of the stretch peak of isocyanate at $2270cm^{-1}$ in the FT-IR. The silica was incorporated into polyurethane dispersion and casted into film. It was shown that the incorporated silica(1~5wt.%) increased water vapour permeability of the films by 30~100%, and decreased the hydrostatic pressure by 10~40%. From the results, it could be concluded that the appropriate hybridization of silica can increase the breathability of polyurethane dispersion film, while minimizing the loss of hydrostatic pressure.

In-Situ Synthesis of PS/(-)Silica Composite Particles in Dispersion Polymerization Using An ($\pm$) Amphoteric Initiator

  • Hwang, Deok-Ryul;Hong, Jin-Ho;Lee, Jeong-Woo;Shim, Sang-Eun
    • Macromolecular Research
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    • v.16 no.4
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    • pp.329-336
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    • 2008
  • Core/shell ($\pm$)PS/(-)silica nanocomposite particles were synthesized by dispersion polymerization using an amphoteric initiator, 2,2'-azobis [N-(2-carboxyethyl)-2,2-methylpropionamidine] ($HOOC(CH_2)_2HN$(HN=) $C(CH_3)_2CN$=NC $(CH_3)_2C$(=NH)NH $(CH_2)_2COOH$), VA-057. Negatively charged (-6.9 mV) silica was used as the stabilizer. The effects of silica addition time and silica and initiator concentrations were investigated in terms of polymerization kinetics, ultimate particle morphology, and size/size distribution. Uniform hybrid microspheres with a well-defined, core-shell structure were obtained at the following conditions: silica content = 10-15 wt% to styrene, VA-057 content=above 2 wt% to styrene and silica addition time=0 min after initiation. The delay in silica addition time retarded the polymerization kinetics and broadened the particle size distribution. The rate of polymerization was strongly affected by the silica content: it increased up to 15 wt% silica but then decreased with further increase in silica content. However, the particle size was only marginally influenced by the silica content. The zeta potential of the composite particles slightly decreased with increasing silica content. With increasing VA-057 concentration, the PS microspheres were entirely coated with silica sol above 1.0 wt% initiator.

Effect of Coagulant Type on the Silica Dispersion and Properties of Functionalized RAFT ESBR Silica Wet Masterbatch

  • Kim, Woong;Ryu, Gyeongchan;Hwang, Kiwon;Song, Sanghoon;Kim, Wonho
    • Elastomers and Composites
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    • v.55 no.3
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    • pp.167-175
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    • 2020
  • Various studies have been conducted to improve silica dispersion of silica filled tire tread compounds; among them, silica wet masterbatch (WMB) technology is known to be suitable for manufacturing silica filled compounds that have high silica content and high dispersibility. Till now, the WMB study is focused on the natural rubber (NR) or emulsion styrene-butadiene rubber (ESBR) that does not have a silica-affinity functional group, and a study of NR or ESBR having a silica-affinity functional group is still not well known. Unlike the dry masterbatch technology, the WMB technology can solve the problems associated with the high Mooney viscosity when applied to silica-friendly rubber. However, a coagulant suitable for each functional group has not yet been determined. Therefore, in this study, different coagulant applied silica WMB was prepared by applying calcium chloride, sulfuric acid, acetic acid, and propionic acid by using a carboxyl group functionalized reversible addition fragmentation chain transfer ESBR. The evaluation of the WMB compounds revealed that the calcium chloride added WMB compound showed excellent silica dispersion, abrasion resistance, and rolling resistance.

Improvement of the Filler Dispersion in Silica-Filled SBR Compounds Using Low Molecular Weight Polybutadiene Treated with Maleic Anhydride (Maleic Anhydride로 처리된 저분자량 폴리부타디엔을 이용한 실리카로 보강된 SBR 배합물에서 충전제 분산성 항상)

  • Choi, Sung-Seen
    • Elastomers and Composites
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    • v.41 no.1
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    • pp.10-18
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    • 2006
  • Influence of low molecular weight polybutadiene (liquid PB) treated with maleic anhydride on properties of a silica-filled SBR compounds was studied. Silica dispersion was improved by adding liquid PB. The liquid PB treated with maleic anhydride (liquid MAPB) was found to be more effective for the improvement of silica dispersion than the liquid PB without maleic anhydride (liquid NPB). Viscosity of the SBR compound decreased by adding the liquid PB. The crosslink density decreased with increase of the liquid PB content and the cure rate became slower with increasing the liquid PB content. Considering the experimental results, it was believed that addition of small amount of the liquid PB (less than 5 phr) was desirable to improve properties of silica-filled SBR compounds.

Effects of Intermeshing Rotor for Dispersion of Silica Agglomerates in SBR/BR Compound (Intermeshing Rotor의 구조가 SBR/BR 합성고무 복합소재의 실리카 분산에 미치는 영향의 비교)

  • Kim, Sung-Min;Kim, Kwang-Jea
    • Polymer(Korea)
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    • v.36 no.5
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    • pp.637-642
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    • 2012
  • The effects of mixing geometry (intermeshing vs. tangential rotor) for the dispersion and distribution of silica agglomerates in SBR/BR compound were investigated. Silica dispersion and distribution were found to be better with the intermeshing rotor compared to the tangential rotor. It was concluded that the intermeshing rotor compared to the tangential rotor delivered a higher shear stress due to interlocked rotor geometry to silica agglomerates leading to better dispersity and distribution of silica in the agglomerates.

Preparation of Organic Dye-Inorganic Silica Hybrid Pigment and It's Application for Inkjet Dispersion Ink (유기 염료-무기 실리카 하이브리드 안료의 제조와 분산잉크로서 응용)

  • Jeon, Young-Min;Kim, Jong-Gyu;Gong, Myoung-Seon
    • Korean Journal of Materials Research
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    • v.16 no.7
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    • pp.422-429
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    • 2006
  • Studies were performed on preparation of organic-inorganic hybrid silica dye in a dispersing ink system. The silica was subjected to surface modification using 3-aminopropyltrimethoxysilane (APTMS) in order to promote the chemical reactivity of the raw silica. On the surfaces of the aminosilane-functionalised silica, red vinylsulfone-containing azo dye was adsorbed. The dye was found to have chemically reacted with the aminosilane-grafted silica surface, which was proven by FT-IR spectra. Studies on morphology and microstructure were performed employing scanning electron microscopy. The SEM micrographs and particle size distributions showed that a homogeneous pigment can be obtained employing silica as a core. Particle size distribution was also examined using the technique of dynamic light scattering. The ensuing pigment was subjected to various physicochemical evaluation such as inkjet property, storage stability, color change as inkjet ink using printer, spectrophotometric, microscopic techniques. Studies on hybrid dyes from the silica surface demonstrated that, in general, stable pigments for inkjet dispersion ink were obtained.

Electrodeposition of Permalloy-Silica Composite Coating (전기도금법을 이용한 퍼멀로이-실리카 복합도금)

  • Jung, Myung-Won;Kim, Jong-Hoon;Lee, Heung-Yeol;Lee, Jae-Ho
    • Journal of the Microelectronics and Packaging Society
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    • v.17 no.4
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    • pp.83-88
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    • 2010
  • The composite electroplating is accomplished by adding inert materials during the electroplating. Permalloy is the term for Ni-Fe alloy and it is used for industrial applications due to its high magnetic permeability. Microhardness for microdevices is enhanced after composite coating and it increases the life cycle. However, the hydroxyl group on the silica makes their surface susceptible to moisture and it causes the silica nanoparticles to be agglomerated in the aqueous solution. The agglomeration problem causes poor dispersion which eventually interrupts uniform deposition of silica nanoparticles. In this study, the dispersion of silica nanoparticles in the permalloy electroplated layer is reported with variation of additives and sonication time. Longer sonication period guaranteed better silica nanopowder dispersion and sonication period also influenced on composition of deposits. The amount of silica nanopowder codeposition and surface morphologies were influenced with variation of additives. In alkaline bath, smooth surface morphology and relatively high contents of silica nanopowder codeposition were obtained with addition of sodium lauryl sulfate.