Effect of kaolinite subgroup aluminosilicates and magnesium spinel hybrid fillers on the properties of PTFE composites

This study investigates novel hybrid filler systems combining kaolinite subgroup aluminosilicates with magnesium spinel (MS) for enhancing polytetrafluoroethylene (PTFE) composites. The synergistic effect between fillers enables structural matrix modification and improved tribological performance. Results demonstrate exceptional wear resistance improvements: kaolinite + MS composites showed 1400-fold enhancement, while halloysite + MS systems achieved 262-fold improvement versus pristine PTFE. XRD and SEM analyses revealed that the introduction of the hybrid filler complex leads to the rearrangement of the polymer’s supramolecular structure. Specifically, the formation of spherulite-like structures and a 25% increase in the degree of crystallinity of the composites were observed. Composites with kaolinite and MS retain their deformation-strength characteristics at the level of the original PTFE. In contrast, composites containing halloysite and magnesium spinel demonstrated a 30% increase in elastic modulus and a 13% enhancement in Shore A hardness but showed deterioration in tensile properties: a 55% reduction in tensile strength and a 95% decrease in elongation at break. SEM and IR spectroscopy confirmed the occurrence of tribo-oxidative processes during friction, leading to the formation of a secondary protective structure that prevents further abrasion of the polymer material. The findings establish a structure-property relationship pivotal for developing advanced PTFE-based materials for demanding tribological applications.