SURFACE-MORPHOLOGY AND NANOSTRUCTURE OF HIGH-MODULUS POLYETHYLENE FIBER

Surface morphology and nanostructure of the ultrahigh molecular weight polyethylene fiber Spectra 900 were examined by atomic force microsco py underwater, with height and lateral force registration. Non-uniform surface morphology, where the bundles of microfibres are covered by i nterwoven randomly oriented fibrils (''hairs'') and twisted ribbons, w as registered in the large scale images. The nanofibril elements detec ted in the bundles and in the ''hairs'' are 5 - 8 nm in width. Periodi cal stripes found by lateral force measurement on individual fibrils ( long period) were assigned to sequences of crystalline and less-ordere d regions. The repeat distance of the long period varies from place to place being in the range of 10 - 20 nm. The complexity of the polyeth ylene fiber structure is supported by visualizing large crystallites, which were found in the ribbons split from the fiber surfaces.