Effect of Water-Soluble Polymers on the Rheology and Microstructure of Polymer-Modified Geopolymer Glass-Ceramics

• Published in: Materials Vol. 17; no. 12; p. 2856
• Main Authors: Migliore, John M, Hewitt, Patrick, Dingemans, Theo J, Simone, Davide L, Monzel, William Jacob
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 11-06-2024; MDPI
• Subjects: Addition polymerization; Aluminosilicates; Aluminum silicates; Analysis; Aramid fibers; Cement; Ceramic materials; Ceramic mold casting; Ceramics; Composite materials; composites; Crack initiation; Crystallization; Electron microscopy; Fourier transforms; geopolymer; Geopolymers; Glass ceramics; Hardness; Heat resistance; Heat treatment; Mechanical properties; Metakaolin; Microstructure; microstructure-prefiring; Modulus of elasticity; Nanoindentation; Particle size; Phosphates; Phosphoric acid; Polyamide resins; Polymer industry; polymer-modified; Polymers; Polyvinyl alcohol; Porosity; Powders; Rheological properties; Rheology; Sodium; Sol-gel processes; Tensile strength; Water; Water chemistry; Water soluble polymers; composites; geopolymer; high-performance; hybrid; rheology; polymer-modified; porosity; Sol-gel processes; glass-ceramics; microstructure-prefiring
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma17122856

This work explores the effects of rigid (0.1, 0.25, and 0.5 wt. %) and semi-flexible (0.5, 1.0, and 2.5 wt. %) all-aromatic polyelectrolyte reinforcements as rheological and morphological modifiers for preparing phosphate geopolymer glass-ceramic composites. Polymer-modified aluminosilicate-phosphate geopolymer resins were prepared by high-shear mixing of a metakaolin powder with 9M phosphoric acid and two all-aromatic, sulfonated polyamides. Polymer loadings between 0.5-2.5 wt. % exhibited gel-like behavior and an increase in the modulus of the geopolymer resin as a function of polymer concentration. The incorporation of a 0.5 wt. % rigid polymer resulted in a three-fold increase in viscosity relative to the control phosphate geopolymer resin. Hardening, dehydration, and crystallization of the geopolymer resins to glass-ceramics was achieved through mold casting, curing at 80 °C for 24 h, and a final heat treatment up to 260 °C. Scanning electron microscopy revealed a decrease in microstructure porosity in the range of 0.78 μm to 0.31 μm for geopolymer plaques containing loadings of 0.5 wt. % rigid polymer. Nano-porosity values of the composites were measured between 10-40 nm using nitrogen adsorption (Brunauer-Emmett-Teller method) and transmission electron microscopy. Nanoindentation studies revealed geopolymer composites with Young's modulus values of 15-24 GPa and hardness values of 1-2 GPa, suggesting an increase in modulus and hardness with polymer incorporation. Additional structural and chemical analyses were performed via thermal gravimetric analysis, Fourier transform infrared radiation, X-ray diffraction, and energy dispersive spectroscopy. This work provides a fundamental understanding of the processing, microstructure, and mechanical behavior of water-soluble, high-performance polyelectrolyte-reinforced geopolymer composites.