Accelerated Alkaline Attack of 3D Printing Polymers to Assess Their Durability in Geopolymer-Based Matrices

Geopolymers exhibit high mechanical performance and low CO2 emissions, and have garnered interest in the construction sector. The brittleness of geopolymer matrices has led to a demand for materials to reinforce them and make them suitable for applications involving tensile or dynamic loading, such as reinforcements produced with 3D printing. However, the durability of polymers currently used in 3D printing in geopolymer matrices is unknown. The properties of polylactic acid (PLA) and poly(ethylene terephthalate)-glycol (PETG), when immersed in an alkaline solution that simulates the pore water of geopolymer matrices, were assessed with weight monitoring, Fourier transform infrared spectroscopy, thermal analysis, and direct tensile tests. The results showed that new carbonyl compounds are formed in the extension of the polymeric chains, which could be associated with the oxidation of the chains. PLA presented a weight loss of 35.83% and a decrease in tensile strength of 45.62%. PETG showed no significant changes in properties, indicating its good durability in geopolymer matrices.