Improvement of Adhesion of Kevlar Fiber to Poly(methyl methacrylate)

Abstract

The surface of Kevlar fibers can be modified by some chemicals through metalation reaction in a solution of methylsulfinylcarbanion and dimethylsulfoxide (DMSO) [Takayanagi et al., Rep. Prog. Polym. Phys. Jpn., 28, 243 (1985)]. In this study, the functional groups introduced to the surface of Kevlar fibers were identified by means of ESCA, referring to the atomic ratios of unmodified Kevlar. The adhesion of the fibers to poly(methyl methacrylate) (PMMA) was evaluated by a single fiber pull-out test. The carboxymethylated and epoxy-reacted fibers showed the strongest affinity to PMMA compared with the untreated fiber and the one having a less-polar surface layer. After the pull-out test, the fiber was observed by SEM to survey the fracture mechanisms. It was observed by SEM that the fiber adhered to PMMA, resulting in both modes of fracture: one case was a strip of fiber skin torn out from the fiber surface and another case, the matrix resin of PMMA was fractured, the residue of which adhered to the fiber surface. Introduction of polar groups such as carboxy and hydroxy groups to the fiber surface layer was most effective in increasing pull out strength.