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Article
Publication date: 9 November 2010

Peter Greenwood

The purpose of this paper is to investigate epoxysilane‐modified silica sols as surfactant‐free inorganic pigments dispersants and as co‐binders/reinforcing agents for…

Abstract

Purpose

The purpose of this paper is to investigate epoxysilane‐modified silica sols as surfactant‐free inorganic pigments dispersants and as co‐binders/reinforcing agents for silicate paints.

Design/methodology/approach

The performance of epoxysilane‐modified silica sols as dispersants for titania was studied using a polyacrylate‐based dispersant as reference. Furthermore, the effect of the addition of silica sols, with or without silane modification, to potassium silicate on binder properties was investigated.

Findings

Significant improvements were obtained in stability towards settling in water‐based titania pigments pastes and in light‐scattering efficiency (as much as 50 per cent) for the optimal size of the silica particle of 5 nm. The number of silane molecules per nm2 silica particle surface must exceed a critical value of at least 1 molecule of epoxysilane per nm2 particle surface. Additionally, improved stability towards gelling, water resistance and film‐forming properties of sol‐silicate binder mixes were achieved for epoxysilane‐modified silica sols.

Research limitations/implications

Only epoxysilane‐modified silica sols were studied in this report. Titania pigment was examined but other important pigments (e.g. iron oxides) remain to be studied. In addition, only sol‐silicate mixes were investigated and not fully formulated silicate paints.

Practical implications

A method that produces stable, high‐performing, surfactant‐free inorganic pigments pastes. Furthermore, stable, high‐ratio, sol‐silicate binders can be obtained with improved water resistance and film properties for use in silicate paints.

Originality/value

The present method provides an easy route to obtain stable surfactant‐free inorganic pigments pastes, as well as makes stable, high‐ratio, sol‐silicate mixes/paints.

Details

Pigment & Resin Technology, vol. 39 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 13 September 2011

Peter Greenwood and Borje Gevert

The purpose of this paper is to study methods of reacting the surface of the particles of silica sols with silanes, primarily gamma‐glycidoxypropyltrimethoxysilane (GPTMS…

Abstract

Purpose

The purpose of this paper is to study methods of reacting the surface of the particles of silica sols with silanes, primarily gamma‐glycidoxypropyltrimethoxysilane (GPTMS) and study some basic properties of the modified sols and the nature and structure of the silane groups attached to the particle surface.

Design/methodology/approach

The surface of the silica particles was modified by reacting the silica sols with aqueous solutions of silanes, chiefly GPTMS. The presence and structure of silane groups on the particle surface were established by Si‐NMR and C‐NMR, respectively.

Findings

Several silanes were studied but silica sols could be readily modified only with GPTMS and glycidoxypropylmethoxydiethoxysilane (GPMDES), most readily if the silanes were pre‐hydrolysed in water. Higher degrees of silylation were preferably done by continuous addition of silane. Lower degrees of modification can be achieved at room temperature by the stepwise addition of the silane solution. The silylation of the silica surface with GPTMS significantly reduces the number of charged surface groups and silanol groups. GPTMS binds covalently to the silica surface and the epoxy ring opens and transforms into a diol. Silica sols modified with GPTMS and GPMDES are stable toward aggregation.

Research limitations/implications

Only organo‐reactive silanes were studied.

Originality/value

This is the first work to study the modification by silanes of silica aquasols with high concentrations of silica. The silane modification can extend the use of silica to areas of applications previously inaccessible to silica sols.

Details

Pigment & Resin Technology, vol. 40 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 12 August 2019

Junrui Zhang, Guojun Jiang, Tianhao Huang, Jun Xie and Da Shi

The paper aims to provide a facile approach to the synthesis of polyurethane–silica nanocomposites by introducing self-made aqueous silica sols with different particle…

Abstract

Purpose

The paper aims to provide a facile approach to the synthesis of polyurethane–silica nanocomposites by introducing self-made aqueous silica sols with different particle sizes into polyurethane materials. This paper investigates the effects of the silica nanoparticles on the polyester polyol, as well as the physical properties and transmittance of the hybrid polyurethane coatings.

Design/methodology/approach

Colloidal silica particles of different sizes were obtained using a sol–gel process and were then embedded into polyester polyol by in-situ polymerization. These polyester polyol–silica resins were synthesized using an azeotrope process, using xylene to remove the water generated in the system and present in the dispersion medium for the colloidal silica. The polyester polyol–silica resins were further cured using isocyanate trimers to form polyurethane–silica hybrid films.

Findings

The paper observed that the viscosity of the polyester polyol–silica nanocomposite resins increased and their appearance changed from transparent to ivory white as the particle size of the added silica was increased. It was found that increasing the hydroxyl content of the silica improved the film transmittance in the visible light region. However, the transmittance decreased sharply once the diameter of the silica particles reached 100 nm.

Research limitations/implications

Because of the limitation of experimental conditions, some performances have not been tested. Therefore, researchers are encouraged to conduct further tests.

Practical implications

The paper provides a method of preparing hybrid polyurethane film by using silica; the results indicate that the introduction of nano-silica can improve the wear resistance and glass transition temperature of polyurethane coatings.

Originality/value

The results obtained in this study will be extremely useful to enhance the understanding of organic–inorganic hybrid materials.

Details

Pigment & Resin Technology, vol. 48 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 11 January 2011

Vilas D. Athawale and Mona A. Kulkarni

The aim of this paper is to synthesise polyester/silica hybrid resins and their hybrid polyurethanes via in situ (IS) and blending (BL) methods and to evaluate the effect…

Abstract

Purpose

The aim of this paper is to synthesise polyester/silica hybrid resins and their hybrid polyurethanes via in situ (IS) and blending (BL) methods and to evaluate the effect of preparation method, interaction type and silica content on the physico‐chemical and thermal properties of polyurethane/silica (PU/Silica) hybrid coatings.

Design/methodology/approach

Silica particle‐containing silica sol was prepared according to Stöber method using tetraethylorthosilicate as the precursor and then introduced into polyester matrix by in situ and direct blending method. The modified polyester/silica resin was further crosslinked with TMP‐TDI adduct to synthesise PU/Silica hybrid coatings and studied for thermo‐mechanical, physico‐chemical properties.

Findings

It was found IS polymerisation caused more polyester segments to chemically bond onto the surface of silica particles than BL process. Results also reveal that due to stronger interaction between silica particles and PU matrix, hybrid resins prepared by IS method confers better properties than BL method and exhibit optimal properties at the critical concentration of 8 wt% silica.

Research limitations/implications

In the present study, silica particles are used to modify properties of polyurethane resins. Many other countless combinations in terms of inorganic filler or organic matrices can be explored to obtain a wide range of interesting properties and applications.

Practical implications

The results obtained in this study will be extremely useful to enhance the understanding of this class of hybrid materials.

Originality/value

Hybrid organic‐inorganic networks offer a new area of material science that has extraordinary implications for developing novel materials that exhibit a diverse range of multi‐functional properties.

Details

Pigment & Resin Technology, vol. 40 no. 1
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 10 August 2018

Chao-Ching Chang, Feng-Hsi Huang and Liao-Ping Cheng

The purpose of this paper is to investigate the effects of dipentaerythritol hexaacrylate (DPHA) and 3-(trimethoxysilyl)propyl methacrylate-modified silica nanoparticles…

Abstract

Purpose

The purpose of this paper is to investigate the effects of dipentaerythritol hexaacrylate (DPHA) and 3-(trimethoxysilyl)propyl methacrylate-modified silica nanoparticles (MSiO2) contents on the performances of the Disperse Red 1 (DR1)-grafted-silica/poly(acrylate) color hard coatings.

Design/methodology/approach

The organic dye DR1 was silylated by reaction with the coupling agent 3-isocyanatopropyltriethoxysilane in methyl ethyl ketone. The silylated-DR1 thus obtained was grafted on MSiO2 to form dye-grafted silica (GSiO2). This hybrid dye was then UV-cured with the cross-linking agent, DPHA, to yield color coatings. Thermal durability of the coatings was evaluated based on their CIE (international commission on illumination) chromaticity coordinates and UV/Vis transmittances.

Findings

The results indicated that GSiO2-coatings could tolerate thermal attack better than pristine DR1-coatings or dye-absorbed silica (DSiO2)-coatings because of the fact that DR1 was more finely dispersed in the polymer binder when covalently bonded to the silica particles. Under optimal conditions, coatings with very small change of saturation and hue after high-temperature treatments were obtainable. These coatings appeared transparent, had 3H-6H pencil hardness and adhered perfectly onto the poly(methyl methacrylate) substrates.

Practical implications

Dye-grafted color coatings may find applications such as color filter photoresists for displays, microelectronics, printed circuit boards, etc.

Originality/value

The performances of the coatings were evaluated in terms of mechanical strength, adherence to the substrate, transmittance and color stability against heat treatments, which have not been disclosed. Also, using a newly developed triangular composition diagram, suitable ranges for preparing useful color coatings were accessed. The present method deserves further research studies on green and blue dyes.

Details

Pigment & Resin Technology, vol. 48 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 7 March 2016

Haibao Lu, Yongtao Yao, Jinying  Yin and Long Lin

This paper aims to study the synergistic effect of self-assembled carboxylic acid-functionalised carbon nanotube (CNT) and nafion/silica nanofibre nanopaper on the…

Abstract

Purpose

This paper aims to study the synergistic effect of self-assembled carboxylic acid-functionalised carbon nanotube (CNT) and nafion/silica nanofibre nanopaper on the electro-activated shape memory effect (SME) and shape recovery behaviour of shape memory polymer (SMP) nanocomposite.

Design/methodology/approach

Carboxylic acid-functionalised CNT and nafion/silica nanofibre are first self-assembled onto carbon fibre by means of deposition and electrospinning approaches, respectively, to form functionally graded nanopaper. The combination of carbon fibre and CNT is introduced to enable the actuation of the SME in SMP by means of Joule heating at a low electric voltage of 3.0-5.0 V.

Findings

Nafion/silica nanofibre is used to improve the shape recovery behaviour and performance of the SMP for enhanced heat transfer and electrical actuation effectiveness. Low electrical voltage actuation and high electrical actuation effectiveness of 32.5 per cent in SMP has been achieved.

Research limitations/implications

A simple way for fabricating electro-activated SMP nanocomposites has been developed by using functionally graded CNT and nafion/silica nanofibre nanopaper.

Originality/value

The outcome of this study will help to fabricate the SMP composite with high electrical actuation effectiveness under low electrical voltage actuation.

Details

Pigment & Resin Technology, vol. 45 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 1 July 1982

Anne J. Walton

Thixotropy can be regarded as the loss of viscosity in a paint or other material that is brought about by mechanical agitation, and where the viscosity continues to…

Abstract

Thixotropy can be regarded as the loss of viscosity in a paint or other material that is brought about by mechanical agitation, and where the viscosity continues to decrease provided that this disturbance is continued for a period of time. Conversely, when the mechanical force is removed, the material then increases in viscosity and this recovery toward the initial structure continues to take place over a period of time. Sometimes the time dependency of the viscosity is vanishingly small so that the material is then properly referred to as pseudoplastic. In most of the literature, however, it is not usually possible to differentiate between thixotropy and true pseudoplasticity and therefore both kinds of structure are included in this review as they each are destroyed by mechanical agitation and recover when this is discontinued.

Details

Pigment & Resin Technology, vol. 11 no. 7
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 26 June 2009

Da‐jing Fang, Xu‐hui Mao, Ye‐ming Zhang, Zhi‐liang Chen, Min Liu and Fu‐xing Gan

The purpose of this paper is to study the compound effect between silane and cerium salts in the passivation process of chemical conversion treatment of zinc.

Abstract

Purpose

The purpose of this paper is to study the compound effect between silane and cerium salts in the passivation process of chemical conversion treatment of zinc.

Design/methodology/approach

Chemical conversion treatment using 3‐Glycidoxypropyltrimethoxysilane on zinc is investigated as an alternative treatment to chromate conversion. The surface chemistry of the silane‐treated samples is investigated with mass change measurements, polarization curves, electrochemical impedance spectroscopy (EIS) and the salt spray tests (SST). The surface morphology of samples was studied using a scanning electron microscope.

Findings

The polarization curves, EIS and SST data are in agreement. On the surface of zinc, the silane formed a compound with the cerium, thus enhancing the adhesion and corrosion resistance of the polymer film.

Originality/value

There have been few reports on the compound effects of silanes and cerium salts in the passivation process. The mechanism of this compound effect may be due to the ability of Ce3 + ions to gain access to the interface through tiny cracks or micropores in the cross‐linking structure of GPS polymer films on zinc, and the subsequent oxidation of Ce3 + to Ce4 + by H2O2 may result in a barrier effect between the electrolyte and the metallic substrate.

Details

Anti-Corrosion Methods and Materials, vol. 56 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 August 2007

Chao-xia Wang, Mao Li, Guang-wei Jiang, Kuan-jun Fang and An-li An-li

The cotton fabrics were surface modified for water repellent finishing with silicon sol, which was prepared with the tetraethoxysilane(TEOS) and solvent ethanol, catalyzer…

Abstract

The cotton fabrics were surface modified for water repellent finishing with silicon sol, which was prepared with the tetraethoxysilane(TEOS) and solvent ethanol, catalyzer HCl, water and modified with additives, such as Methyltriethoxysilane(MTEOS), Octyltriethoxysilane(OTEOS) and Hexadec-ltrimethoxysilane(HTEOS). As a result, acceptable water repellence could only be achieved via the addition of longer chain length additives such as OTEOS, HTEOS, while the use of additives containing a shorter alkyl chain length such as MTES led to insufficient water repellence. The factors which influence contact angles were examined. Excellent water repellent properties could be achieved on the cotton fabrics treated with the silica sols by twice dip and pad and cured at 160°. The silica sol preparation preference conditions were with TEOS: H2O: EtOH=1: 5: 8 (mol) by stirring for 6 hours at 65°C which was added with HTEOS. The water repellence contact angle was able to be reached around 140° and the hydrostatic pressure was 46cm.

Details

Research Journal of Textile and Apparel, vol. 11 no. 3
Type: Research Article
ISSN: 1560-6074

Keywords

Content available
Article
Publication date: 4 January 2013

Peter Greenwood

Abstract

Details

Pigment & Resin Technology, vol. 42 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

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