Structure and mechanical behavior of nylon-6 fibers filled with organic and mineral nanoparticles. I. Microstructure of spun and drawn fibers

The crystalline structure and fibrillar texture of nylon-6 fibers filled with nanosized particles were investigated using wide-angle and small-angle X-ray scattering. As-spun fibers filled with organic nanoparticles consisting of aromatic polyamide-like hyperbranched molecules with amine-terminating groups exhibited strong modification of both the molecular orientation and the crystalline structure compared with that of unfilled spun fibers. Montmorillonite-filled fibers mainly exhibited orientation improvement. The differences are discussed in terms of the rheological and nucleating effects during spinning. Drawing at 140 °C involves structural changes that resulted in the three kinds of fibers having a similar crystalline form and molecular orientation. In parallel, after significant strain-induced changes, the microfibrillar texture of the various fibers displayed subtle differences at the ultimate stage of drawing. The changes in the fibril long period and fibril radius as a function of draw ratio are discussed in terms of the two sequential deformation processes of microfibril stretching and microfibril slipping. The occurrence of interfibrillar strain-induced cavitation is discussed in relation to the nature of the interactions between the filler and the nylon-6 matrix. And, finally, the mechanical properties are discussed in relation to the filler–matrix interaction. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3876–3892, 2004