Characterization of the surface hydrolysis of kevlar-49 fibers by diffuse reflectance FTIR spectroscopy

A modified diffuse reflectance technique is used to characterize the surface hydrolysis of Kevlar‐49 fibers. Treatment with 10 wt% NaOH solution produces carboxylate groups on the surface which increase rapidly up to treatment times of about 20 min at room temperature or 50 min in boiling solution. After this maximum the carboxylate groups decrease and then level out. This behavior can be explained by considering the increase as due to hydrolysis of the surface amide groups, competing with the decrease due to removal of the extensively hydrolyzed, fragmented molecules into the treatment solution. Our results shows that mild conditions (10 wt% NaOH and room temperature) as well as relatively small treatment times (less than 20 min) can be used for modifying the surface of the Kevlar‐49 fiber without destroying the skin and thus deteriorating the mechanical properties of the fiber.