The electron microscope characterization of the fine structure of nylon 6: II. On the rearrangement of the structure during cold-drawing

Abstract

Abstract:The transmission electron microscope (TEM) visualization of the supermolecular structure of cold-drawn, oriented nylon 6 bulk material (bristles) by stained ultrathin sections is reported. For evaluating the electron micrographs optical diffraction (OD) has been applied in comparison with small angle X-ray scattering (SAXS). The deformation of the spherulites was followed by polarization microscopy. In addition, investigations were carried out on commercial nylon 6 fibres. As the main result a transverse structure was revealed within the drawn samples at draw ratios between 2 = 4 and 4.5, consisting of mosaic crystals which show some lateral alignment. The structure is described by a modified layer lattice model. While the long period may increase slightly during drawing, the crystallite thickness remains almost constant. Fibres with 2 = 3.4 show a similarly oriented structure though the lateral alignment of the crystals is not so pronounced.

Changes in the morphology of bulk spherulitic nylon 6 due to plastic deformation

“…Therefore, only the final stages (X = 4) of disorganized fine structure within the still-visible contours of previously existing spherulites could be studied in detail by them. 27 In our experiments, we have used materials, specimen geometries, and a form of deformation which led to natural draw ratios in the range of about 2.5, where the microvoiding phenomenon is particularly prevalent. These experimental conditions, coupled with our use of 0s04 at 4 °C to fix under stress the deformation damage in stretched specimens, made it possible to reveal clearly these deformation-induced damage zones in TEM.…”

The Structure and Properties of Typical Melt-spun Fibres

“…On the other hand, highly ordered polyester fibres were produced [HI] through a combination of orientated crystallization and drawing at high temperatures. Cold-drawn nylon 6 fibres with draw ratios of 4-4.5 were found [112] to exhibit a structure that represented an intermediate state between a fibrilar and a lamellar morphology. The elastic modulus and tensile strength of fibrous material were explained L113] as functions of draw ratio by means of a microfibrillar model of fibrous structure.…”

“…Electron microscopy has shown that the characterization of the rearrangement of the structure during cold drawing is possible [272]. All the above techniques can be successfully used to analyse the proportions of alpha, beta, and gamma fractions in the crystalline structure of nylon 6.…”

“…Cold-drawn nylon 6 under the electron microscope [272] exhibits a structure that represents an intermediate state between a fibrillar and a lamellar morphology. The influence of cold drawing and annealing on alpha, beta, and gamma dispersions was discussed by Kunugi et al [273].…”

“…The effects of drawing and heat treatment on the structure of various melt-spun fibres were investigated by various authors [107][108][109][110][111][112][113]. Problems associated with the production of ultrafine synthetic fibres from mixtures of polymer melts were examined by Sizevich and Tsebrenko [109].…”