| Physical properties and microstructures of poly(phospho-siloxo) and poly(sialate-siloxo) networks from two metakaolins |
| C. Banenzoué1,2, C. N. Bewa1, D. Fotio3, H. K. Tchakouté1,4, B. T. Tchanga1, C. H. Rüscher4 |
1Laboratory of Analytical Chemistry, Faculty of Science, Department of Inorganic Chemistry , University of Yaounde I , P.O. Box 812 , Yaounde , Cameroon
2Faculty of Science , The University of Douala , P.O. Box 24157 , Douala , Cameroon
3Department of Chemistry in Higher Teacher Training College , University of Maroua , P.O. Box 55 , Maroua , Cameroon
4Institut Für Mineralogie , Leibniz Universität Hannover , Callinstrasse 3 , 30167 Hannover , Germany |
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Received: October 31, 2020; Revised: April 10, 2021 Accepted: April 28, 2021. Published online: July 31, 2021. |
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| ABSTRACT |
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The aim of this investigation is to compare the properties of poly(phospho-siloxo) and poly(sialate-siloxo) networks. Commercial sodium waterglass and sodium waterglass from rice husk ash were used as alkaline reagents and phosphoric acid with molarities 8 and 10 M was used as acid reagents. Local metakaolin and commercial ones containing 0.99 and 0.0% of Fe2O3, respectively, were used as aluminosilicate sources. The physical properties of the prepared poly(phospho-siloxo) and poly(sialate-siloxo) networks were monitored by measuring the apparent and absolute density. The microstructures were assessed by scanning electron microscopy and mercury intrusion porosimetry. The engineering property was checked by the determination of their compressive strengths. The results indicated that the apparent densities of poly(phospho-siloxo) and poly(sialate-siloxo) networks are in the ranges 1.918–2.177 and 1.814–1.959 g/cm3, respectively, while their absolute densities are not signifi cantly diff erent. Their compressive strengths are ranging from 14.21 to 30.03 and 50.22 to 75.77 MPa, respectively. The average pore diameters of the specimens from acid reagents are between 30.0 and 83.9 nm whereas those from alkaline reagents are between 8.3 and 14.8 nm. The log diff erential intrusion versus pore size diameters showed that the obtained products using acid and alkaline solutions are ranging from 6000 to 110,000 nm and 5.59 to 13.84 nm, respectively. This indicates that poly(phospho-siloxo) and poly(sialate-siloxo) networks are macroporous and mesoporous materials, respectively. It was found that the chemical and mineralogical compositions and the degree of the purity of the aluminosilicate source could signifi cantly aff ect the physical properties and microstructures of poly(phospho-siloxo) network. |
| Key words:
Metakaolins · Sodium waterglass · Phosphoric acid · Poly(sialate-siloxo) · Poly(phospho-siloxo) · Microstructures |
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