Synthesis and characterization of ionomer-type cements from alkaline-activated kaolinite

Abstract

The objective was to synthesize ionomer-type cements from alkaline-activated kaolinite and describe their setting characteristics, compressive strength and fluoride ion releasing properties. Aluminosilicate phases were visible on XRD spectra with minimal difference between raw and alkaline-activated kaolin. D50 range of sieved powders was 8.10–9.07 μm. Characteristic bands of polyacrylates and tartrates were identifiable in the cements on FTIR. Cements were hydrolytically stable with mixing and setting times of 60s and 135–240 s, respectively. Mean compressive strength increased over time, highest value 3.24 MPa recorded for Kaolin100 after 28 days, and significantly different within the group (F = 76.64, p = 0.000). Cement containing fly ash (FA) exhibited fluoride ion release capabilities with Kaolin80FA20 having the highest 0.69 mmol/L at 60 min. Mechanically weak but hydrolytically stable ionomer cements can be formulated from alkaline-activated kaolin geopolymers.

Keywords

• Glass ionomer cement
• Geopolymer
• Alkaline-activation
• Kaolinite
• Dental cement