Decoding commercial polymer-modified tile adhesives: mechanistic insights from microstructural, thermal, and mechanical analyses

This study presents a multiscale evaluation of three commercial polymer-modified tile adhesives (K2, M2, S2) compared with an unmodified cement–sand mortar (C), integrating microstructural (SEM/EDS), phase/structural (XRD, XRF, FTIR), surface/colloidal (zeta potential), thermal (TGA/DTG, DSC), physical (density, particle size), workability (flow, open time, slip), and mechanical such as pull-off, tensile, slant shear, compressive, flexural, stress–strain analyses. Polymers were incorporated into hydration products, forming continuous films that strengthen interactions with carbonate-rich fillers, refine pore structure, and modify surface charge. Thermal analysis revealed multi-stage degradation, while physical characterization showed lower density, finer grains, and higher water–cement ratio. Polymer-modified adhesives exhibited improved workability, adhesion, and tensile strength, but reduced stiffness and compressive strength with increased deformability. These findings indicate that performance arises from synergistic interactions among polymer films, fillers, colloidal stabilization, and matrix microstructure, providing a mechanistic framework for optimizing next-generation tile adhesives.