Exploring potential correlation between mechanical and physicochemical properties of aramid fibers under acid/alkali exposure

Aramid fiber products have been widely applied in harsh environments due to their excellent performances. The changes in mechanical properties of fibers in acid/alkali environments and their correlation with physicochemical properties has been an interest point for the materials application. In this study, the tensile strength and failure strain of fibers were analyzed under different acid/alkali treatments to characterize the changes in mechanical properties. Meanwhile, the physicochemical properties of fibers including micromorphology, phase structure, and functional groups were characterized by scanning electron microscope, X-ray diffraction and attenuated total reflection-Fourier transform infrared spectroscopy. The results show that the tensile strength retention ratio firstly increased and then decreased with the increase in treatment time at the same treatment concentration. Multiple characterization results indicated that the physicochemical properties of the treated fibers altered significantly, including surface morphology damage, crystallinity increasing, and the hydrolysis of amide bonds in molecular structure. The jointly results show that the changes in tensile strength and strain of the treated fibers were attributed to the antagonistic result of the reinforced effect of the increased crystallinity and the attenuated effect of hydrolytic degradation. The obtained results can provide a theoretical support to improve our understanding of the correlation between the alterations of mechanical properties and physicochemical properties induced by acid/alkali treatment in harsh environments. This understanding would also help better to develop the composite materials based on the chemically modified fibers. • Effects of acid/alkali exposure with different treatment concentrations and times on mechanical properties of fibers were conducted. • Physicochemical properties of fibers before and after acid/alkali treatment were characterized and compared. • Potential correlation between mechanical and physicochemical properties of fibers was analyzed.