Recent developments on inorganic polymers synthesis and applications

Lemougna, Patrick N.; Wang, Kai-tuo; Tang, Qing; Melo, Uphie Chinje; Cui, Xuemin

doi:10.1016/j.ceramint.2016.07.027

Cited by 142 publications

(56 citation statements)

References 131 publications

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“…In contrast, commercial metakaolins are more expensive, lightly shaded with a generally similar composition and guaranteed particle size distribution. They are manufactured by the calcination of purified kaolin with high kaolinite content under controlled conditions [42,43]. In the process, kaolinite is dehydroxylated to meta-kaolinite.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Kaolin and Kaolinitic Claystones as Raw Materials for Preparing Meta-Kaolinite-Based Geopolymers

Koutník¹

2019

Ceramics - Silikaty

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Geopolymer binders were then prepared by water addition up to an invariable content of 34 wt. %. The binders were finally mixed with quartz sand in a weight ratio of 40:60. The differences in the properties between the two types of clay materials, the changes in these properties due to dehydration and milling, and the impact of the observed differences on the properties of the geopolymer binders (dynamic viscosity, pore size distribution, colour shade) and filled geopolymers (flexural strength, compressive strength, elastic modulus) were investigated. The kaolinitic claystones had a morphology different from the kaolin, characterised by smaller kaolinite plates, significantly lower pore volumes with average pore diameters and a higher impurities content that caused a more intense colour compared to the kaolin. The above-mentioned differences remained unchanged after thermal and mechanical treatment of the starting clay materials. The geopolymer binders prepared from the calcined and milled kaolinitic claystones were darker in colour and had a significantly lower dynamic viscosity (approximately three times) compared to the geopolymer binders prepared from the kaolin. The dynamic viscosity decreased with the decreasing activator content, while the volume and pore size increased. The mechanical properties of all the prepared geopolymers were excellent (compressive strength >50 MPa, bending strength > 7.9 MPa and elastic modulus >15 GPa) up to a ratio of metakaolinite component/alkali activator of 1:1. Comparison of kaolin and kaolinitic claystones as raw materials for preparing metakaolinite-based geopolymers Ceramics-Silikáty 63 (1) 110-123 (2019)

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Section: Introductionmentioning

confidence: 99%

Comparison of Kaolin and Kaolinitic Claystones as Raw Materials for Preparing Meta-Kaolinite-Based Geopolymers

Koutník¹

2019

Ceramics - Silikaty

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“…In this region, the aluminosilicate gel particles will dissolve and generate Si‐O and Al‐O tetrahedrons under the action of the sodium ions. They will be able to induce polymerization and rearrange on the surface of the particles when the two types of tetrahedra are sufficiently concentrated close to the theoretical composition of the NaA zeolite forming the ordered nanocrystalline core . Afterward, with an increase in SiO 4 and AlO 4 polymers, the nanocrystals gradually grow into NaA zeolites.…”

Section: Resultsmentioning

confidence: 99%

“…They will be able to induce polymerization and rearrange on the surface of the particles when the two types of tetrahedra are sufficiently concentrated close to the theoretical composition of the NaA zeolite forming the ordered nanocrystalline core. 5,[18][19][20] Afterward, with an increase in SiO 4 and AlO 4 polymers, the nanocrystals gradually grow into NaA zeolites. These processes mainly depend on the transport of water molecules.…”

Section: Reaction Mechanismmentioning

confidence: 99%

Preparation of NaA zeolite spheres from geopolymer gels using a one‐step method in silicone oil

Liu

Tang

et al. 2017

Int J Applied Ceramic Tech

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A simple one‐step method for the preparation of NaA zeolite spheres using a nonhydrothermal process is introduced in this article. The mechanism of formation of NaA zeolite spheres was studied by the suspension solidification method in both silicone oil and polyethylene glycol. The crystalline phase, micromorphology, and microstructure of the spheres produced were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), and BET specific surface tests. The results demonstrate that geopolymer spheres can directly transform into NaA zeolite spheres in silicone oil but not in polyethylene glycol (PEG). Since the formation process in PEG cannot retain water in the geopolymer spheres, there is no additional medium that can transport and rearrange the aluminate and silicate groups in the geopolymer gel. Thus, the geopolymer gel cannot crystallize to form zeolite crystals.

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“…though other authors report better results at room temperature [9] [10], and others establish a threshold value above 60˚C -70˚C, which would be detrimental for long term strength of GP [11]. Long curing times at relatively low temperature allow the formation of fairly homogeneous samples with highly mechanical strength, whereas breaks of the granular structure of geopolymers are observed at high temperatures [12].…”

Section: Introductionmentioning

confidence: 97%

“…In the case of MK activated with KOH, the experimental design, the parameters affecting, and the prediction of the mechanical properties are scarce or there is none. Since the large size of K + in this system favored the formation of bigger silicate oligomers, matrixes exhibited higher compressive strength and a specific surface area; plus a lower degree of crystallinity and resistance to attack by HCl [11] [25].…”

Section: Introductionmentioning

confidence: 99%

Compressive Strength of Metakaolin-Based Geopolymers: Influence of KOH Concentration, Temperature, Time and Relative Humidity

García-Mejía¹,

Chávez-García²

2016

MSA

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The influence of KOH concentration (8 and 12 M) and curing conditions as temperature (40˚C and 60˚C), time (7 and 28 days) and relative humidity (85% and 95% RH), on compressive strength of metakaolin-based geopolymers (MK-based GP) was evaluated. Derived from the experimental design technique, and using a factorial design 2 K with two replications in the center point, eighteen experiments were conducted. The results reveal that the best performance conditions of geopolymerization to develop a higher compressive strength of 20 MPa are 12 M KOH to 60˚C and 85% RH at 28 curing days. With these conditions, the value of relative humidity of 85%, promotes high strength compact samples, and a maximum of 42 MPa at 90 days. The results of significant, compressive design of GP showed that KOH concentration and curing relative humidity were the most important factors, followed by curing time and temperature. The GP were characterized by XRD, and their evolution on compression strength was followed by SEM.

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Recent developments on inorganic polymers synthesis and applications

Cited by 142 publications

References 131 publications

Comparison of Kaolin and Kaolinitic Claystones as Raw Materials for Preparing Meta-Kaolinite-Based Geopolymers

Comparison of Kaolin and Kaolinitic Claystones as Raw Materials for Preparing Meta-Kaolinite-Based Geopolymers

Preparation of NaA zeolite spheres from geopolymer gels using a one‐step method in silicone oil

Compressive Strength of Metakaolin-Based Geopolymers: Influence of KOH Concentration, Temperature, Time and Relative Humidity

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