Influence of Microcapsule Size and Shell Polarity on the Time-Dependent Viscosity of Geopolymer Paste

Cao, Vinh Duy; Pilehvar, Shima; Bringas, Carlos Salas; Szczotok, Anna M.; Duyen, Nu Bich; Thanh, Hoà Lê; Carmona, Manuel; Rodríguez, Juan F.; Kjøniksen, Anna–Lena

doi:10.1021/acs.iecr.8b01961

Cited by 40 publications

(19 citation statements)

References 23 publications

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“…At the highest shear rate, St‐DVB‐PCM has little effect on Γ 1 for GM. Similar results was also observed for a geopolymer paste (without sand) at the same shear rate 35 . However, at the lowest shear rate (1 s −1 ), St‐DVB‐PCM causes Γ 1 of GM to increase, suggesting a faster reaction.…”

Section: Resultssupporting

confidence: 82%

“…The viscosity of GM (Figure 10A) increases at the start of the reaction ( Γ 1 > 0). This initial slow viscosity increase of geopolymers has been contributed to the formation of geopolymer precursors 35 . This increase is steeper at the lowest shear rate, which is expected since higher shear rates disrupt the reaction process.…”

Section: Resultsmentioning

confidence: 95%

“…However, St‐DVB‐PCM adsorbs more water than the sand it replaces 18 . The reduction of free water in the sample may increase the concentration of the reactants in the liquid phase, thereby increasing the reaction rate 35 …”

Section: Resultsmentioning

confidence: 99%

“…Most previous studies only measure slump, which generally show that MPCM addition increase the water demand to obtain a constant slump value, 34,36 or analogously that adding microcapsules decrease the slump 15,18,36 . More thorough rheological investigations utilizing rheometers or viscosimeters are scarce 35,36 . Shear rate dependencies of Portland cement paste containing MPCM has been examined, and it was found that the pastes went from shear thinning to shear thickening behavior when the amount of superplasticizer was increased 36 .…”

Section: Introductionmentioning

confidence: 99%

“…Shear rate dependencies of Portland cement paste containing MPCM has been examined, and it was found that the pastes went from shear thinning to shear thickening behavior when the amount of superplasticizer was increased 36 . The time‐dependent viscosities of geopolymer pastes containing three different MPCMs have been studied at a constant shear rate 35 . It was found that at the start of the reaction, there was a slow viscosity increase due to the formation of geopolymer precursors, and that these precursors formed faster in the presence of MPCM.…”

Section: Introductionmentioning

confidence: 99%

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The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

et al. 2020

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The effect of microencapsulated phase‐change materials (MPCM) on the rheological properties of pre‐set geopolymer and Portland cement mortars was examined. Microcapsules with hydrophilic and hydrophobic shells were compared. The shear rate dependency of the viscosities fitted well to a double Carreau model. The zero shear viscosities are higher for geopolymer mortar, illustrating poorer workability. The time evolution of the viscosities was explored at shear rates of 1 and 10 s−1. New empirical equations were developed to quantify the time‐dependent viscosity changes. The highest shear rate disrupted the buildup of the mortar structures much more than the lower shear rate. Microcapsules with a hydrophobic shell affect the rheological properties much less than the microcapsules with a hydrophilic shell, due to the higher water adsorption onto the hydrophilic microcapsules. Shear forces was found to break down the initial structures within geopolymer mortars more easily than for Portland cement mortars, while the geopolymer reaction products are able to withstand shear forces better than Portland cement hydration products. Initially, the viscosity of geopolymer mortars increases relatively slowly during due to formation of geopolymer precursors; at longer times, there is a steeper viscosity rise caused by the development of a 3D‐geopolymer network. Disruption of agglomerates causes the viscosities of portland cement mortars to decrease during the first few minutes, after which the hydration process (increasing viscosities) competes with shear‐induced disruption of the structures (decreasing viscosities), resulting in a complex viscosity behavior.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

et al. 2020

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Triphenylphosphine‐containing microcapsules fabricated from Pickering emulsions as a thermal latent curing accelerator for an epoxy/anhydride system

Gou

Zhang

Wei

et al. 2021

Polymer International

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Latent curing accelerators are essential for application to one-component epoxy systems in various industries, such as coatings, adhesives and electronic packaging. Herein, we developed organic-inorganic hybrid microcapsules encapsulating triphenylphosphine (TPP) by Pickering emulsion polymerization of styrene and methoxyethyl methacrylate with dimethoxydiphenylsilane-modified silica nanoparticles as emulsifiers. The microcapsules were further surface-modified by epoxy silane and employed as a thermal latent curing accelerator for an epoxy/anhydride system. Good dispersibility and interfacial bonding of the hybrid microcapsules with the resin matrix were observed. Compared with TPP, the microcapsule-type accelerator endowed the one-component epoxy curing system with significantly enhanced storage stability at room temperature of 25 °C (a pot life of 20 days) and a comparable curing activity at high temperature. The activity of the encapsulated accelerator can be blocked and released rapidly and effectively with increasing temperature to trigger the segmental motion of the polymeric microcapsules. Furthermore, the addition of microcapsules increased the glass transition temperature and thermal stability of the epoxy thermosets owing to the organic-inorganic hybrid character. Moreover, the toughness of the cured resin was also improved. Therefore, the latent curing accelerator demonstrated a promising prospect for application in highperformance one-pot epoxy formulations.

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Metallurgical and Mining Waste Utilization in Preparation of Geo-Polymeric Bricks as the Future Construction Material

Dandekar

Deshmukh²,

Bangalkar

et al. 2021

Innovations in Sustainable Mining

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Influence of Microcapsule Size and Shell Polarity on the Time-Dependent Viscosity of Geopolymer Paste

Cited by 40 publications

References 23 publications

The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

Triphenylphosphine‐containing microcapsules fabricated from Pickering emulsions as a thermal latent curing accelerator for an epoxy/anhydride system

Metallurgical and Mining Waste Utilization in Preparation of Geo-Polymeric Bricks as the Future Construction Material

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