• Elastomers and Composites
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• v.32 no.1
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• pp.11-19
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• 1997

[ ${\gamm}-Glycidoxy$ ] propyl trimethoxy silane, CTBN rubber(carboxyl terminated butadiene acrylonitrile rubber) and GMA(glycidyl methacrylate) were reacted on the surface of silica one by one in existence of TEA(triethylamine) or BPO(benzoyl peroxide). The amount of reactant was $2.5{\sim}5.8%$ of treated silica weight. The treated silica was mixed with epoxy resin and MTHPA(methyl tetrahydro phthalic anhydride) in the range of $0{\sim}60%$(wt.%) of total component. The thermal properties were tested for cured products. By using silica treated with silane/rubber or silane/rubber/vinyl, comparing with 3% of rubber mixed directly, it had 13% higher $T_g$ and 10% lower thermal expansion coefficient at $35{\sim}55%$ of silica contents.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.399-402
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• 2005

In ultra-high strength SFRCC(Steel Fiber Reinforced Cementious Composites), much silica fume are used to improve strength, flowability and durability. Silica fume have merits of filling the voids, enhancement of reheological chracteristics, production of secondary hydrates by pozzolanic reaction in reactive powder concretes. However silica fume has been imported in high-cost in domestic industry, we need to investigate replaceable material in stead of silica fume in a view of economy Therefore, in this paper, in order to investigate replacement of silica fume in ultra-high strength SFRCC we used the granulate blast-furnce slag with finess 4000, 6000, 8000. As a results, we have evaluated that the bigger the finess the more increase compressive strength of ultra-high strength SFRCC using the blast-furnce slag and there was no problem from the viewpoint of flowability and compressive strength when we use blast-furnce $50\%$ with replacement ratio of silica fume

• Elastomers and Composites
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• v.33 no.2
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• pp.75-82
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• 1998

The purpose of this experimental study was to investigate the effects of vulcanization condition on the properties of reinforced rubbers. Rubber reinforcing ability of carbon black was more efficient than other fillers, but tensile properties were not affected by vulcanization condition while vulcanization condition affected the physical properties of rubber compounds with silica and silane treated slica. It was found that silica and silane treated silica filled rubber compounds showed good dynamic properties, rebound, heat build-up, 0 and $60^{\circ}C$ tan $\delta$ compared with carbon black filled rubber compounds. Carbon black filled rubber compounds were higher than silica and silane treated silica filled rubber compounds in total crosslinking density by vulcanization condition. By analysis of crosslinking type, polysulfide crosslinking was the highest in the carbon black filled rubber compounds with decreasing the ratio of sulfur to accelerator, monosulfide crosslinking was the highest in the silane treated silica filled compounds with in-creasing the ratio of sulfur to accelerator.

• Elastomers and Composites
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• v.50 no.3
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• pp.159-166
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• 2015

Silica which is used for reinforcing filler in tire industry is widely known as eco-friendly material exerting $CO_2$ reduction effect through decrease of rolling resistance and improvement of wet grip. Generally silica is classified as a highly polar filler because it contains a large number of silanol (Si-OH) group on its surface. And also silica gives a lower reinforcing effect than carbon black due to its poorer rubber-filler interaction. Therefore silica is treated with silane coupling agent or activator, then following the conventional rubber blend method, vulcanized sheets were prepared using a hot press, and cure characteristics, mechanical properties and abrasion resistance of the test specimens were investigated. It was found that with an increase in the silane coupling agent content the tensile strength, 300% modulus and abrasion resistance increased while Mooney viscosity decreased and crosslink density slightly increased with an increase of activator.

• Transactions on Electrical and Electronic Materials
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• v.14 no.2
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• pp.101-104
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• 2013

The effect of the mixing ratio of spherical silica on the electrical insulation breakdown strength in an epoxy/silica composite was studied. Spherical silicas with two average particle sizes of $5{\mu}m$ and $20{\mu}m$ were mixed in different mixing ratios, and their total filling content was fixed at 60 wt%. In order to observe the dispersion of the silicas and the interfacial morphology between silica and epoxy matrix, scanning electron microscopy (SEM) was used. The electrical insulation breakdown strength was estimated in sphere-sphere electrodes with different insulation thicknesses of 1, 2, and 3 mm. Electrical insulation breakdown strength decreased with increasing mixing ratio of $5/20{\mu}m$ and the thickness dependence of the breakdown strength was also observed.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.133-139
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• 1990

Methacrylate functional silanes with different methylene spacer groups have been synthesized and the orientation effect and absorption behavior of these silane coupling agent were investigated by Fourier transform infrared spectroscopy(FT-IR). The mechanical properties of glass bead/polyester composites are found to be dependent on the spacer group of treated silane coupling agent. The absorption rate of the silane coupling agent onto the fumed silica surface decreases with increasing the number of the methylene spacer in methacrylate functional silanes. Silane molecules containing long spacer groups are adsorbed onto silica slightly bowed with respect to the substrate surface. The relationship between silane molecular structure and mechanical properties of polymer composites is also investigated in order to improve hot/wet properties of glass fiber/polyester composites.

• Korean Journal of Materials Research
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• v.34 no.3
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• pp.175-183
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• 2024

Geopolymer, also known as alkali aluminum silicate, is used as a substitute for Portland cement, and it is also used as a binder because of its good adhesive properties and heat resistance. Since Davidovits developed Geopolymer matrix composites (GMCs) based on the binder properties of geopolymer, they have been utilized as flame exhaust ducts and aircraft fire protection materials. Geopolymer structures are formed through hydrolysis and dehydration reactions, and their physical properties can be influenced by reaction conditions such as concentration, reaction time, and temperature. The aim of this study is to examine the effects of silica size and aging time on the mechanical properties of composites. Commercial water glass and kaolin were used to synthesize geopolymers, and two types of silica powder were added to increase the silicon content. Using carbon fiber mats, a fiber-reinforced composite material was fabricated using the hand lay-up method. Spectroscopy was used to confirm polymerization, aging effects, and heat treatment, and composite materials were used to measure flexural strength. As a result, it was confirmed that the longer time aging and use of nano-sized silica particles were helpful in improving the mechanical properties of the geopolymer matrix composite.

• Elastomers and Composites
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• v.36 no.1
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• pp.37-43
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• 2001

Influence of the filler composition ratio on cure characteristics and bound rubber content of the compounds and on physical properties of the vulcanizates were studied using both silica and carbon black-filled styrene-butadiene rubber (SBR) compounds with the total filler content of 80.0 phr. The bound rubber content increased slightly with increase of the silica content ratio. The viscosity also increased with increasing the silica content ratio, especially increased steeply after the silica content of 60.0 phr. The cure times obtained with a rheometer, t2, t40, and t90, are increased by increasing the silica content ratio and the cure rate decreased. The delta torque increased with the increased silica content ratio. Variation or the modulus with the silica content ratio showed a decreased trend though the delta torque increased. The tan ${\delta}$ at $60^{\circ}C$ decreased with increased of the silica content ratio.

• Elastomers and Composites
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• v.53 no.2
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• pp.57-66
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• 2018

Styrene-butadiene rubber (SBR), reinforced with different contents of silica (with or without modification using silane coupling agents), was prepared by a modified sol-gel method involving hydrolyzation of tetraethoxysilane over an acid catalyst. The structures of the as-prepared samples were characterized using various techniques, such as scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The mechanical properties of the as-prepared samples were discussed in detail. The results revealed an increasing of the storage modulus (G') with increase in the silica content without modification. In contrast, G' decreased after modification using silane coupling agents, indicating a reduction in the silica-silica interaction and improved dispersion of silica in the SBR matrix. Both tensile stress and hardness increased with increase in the silica content (with modification) in the SBR matrix, albeit with low values compared to the samples with un-modified silica, except for the case of silica modified using (3-glycidyloxypropyl) trimethoxysilane (GPTS). The latter observation can be attributed to the special structure of GPTS and the effort of oxygen atom lone-pair.

• 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.