Surface modification of synthetic fibers by excimer laser irradiation

Abstract

AbstractIt was attempted to improve the fiber/rubber adhesion by surface modification of fibers by excimer laser irradiation. The fibers were first treated with a glycidyl ether acrylate compound which is sensitive to UV rays, then cured with a KrF laser and treated with an ordinary RFL (resorcinol formalin rubber latex), and then cured in heat. For poly(ethylene terephthalate) (PET) and poly(p‐phenylene‐3,4′‐oxydiphenylene terephthalamide) (PPODPTA) fibers, the adhesion performances were improved, whereas for poly(p‐phenylene terephthalamide) (PPTA) fibers they were not. In PET fibers, the surface layer was converted into the amorphous state, and therefore the affinities for the treating agents were enhanced. As for the aramid fibers, the copolymer components of the PPODPTA fibers contain crystalline domains, independently, which are oriented sufficiently, leaving almost no amorphous state in which molecules remain relaxed, and are difficult to be fibrillated. On the other hand, the PPTA fibers comprise a skin layer and a core layer composed of fibrils stacked into blocks. Between the blocks, amorphous phases containing a relatively large number of molecular chain ends are present, facilitating the fibrillation. Probably, the molecules in the non‐crystalline state of both of the fibers were relaxed differently, causing different susceptibilities to ablation. This might result in different affinities to the acrylate compound, or different adhesion performances, respectively.