Comprehensive study of polymer fiber surface modifications Part 2: Low-temperature oxygen-plasma treatment

Polyamide fibers were treated with a low-temperature oxygen plasma and the effects on the morphology, chemistry and crystallinity of the material were studied. Topographical results illustrate that changes in the surface morphology of the oxygen-plasma-treated polyamide correlate well with the discharge power and treatment time. The effects can be categorized into three groups: surface cleaning resulting in a smoother surface, surface etching with formation of 'ripple-like' structures of sub-micrometer size, and surface melting with down grading of the material. Chemical studies show that the surface oxygen content of the polyamide increases after oxygen-plasma treatment. The latter induces the formation of many hydroxyl and carboxylic acid functional groups. These groups mainly replace the hydrocarbon or carbonyl groups in the polyamide. Differential scanning calorimetry (DSC) results indicate that a short treatment time does not affect the degree of crystallinity of the polyamide material, while a long plasma-treatment time slightly increases the crystallized fraction.