Morphology of cold‐drawn nylon 66

Abstract

SynopsisA nylon 66 composed of uniformly sized spherulites approximately 50 p in diameter was examined before and after cold drawing by light and electron microscopy of thin sections and by low-angle x-ray diffraction. Spherulites retained their identity through drawing, but the spherulites elongated less than the bulk specimen indicating that relative motion of spherulites must have occurred. The observation of dilations (0.3 p long) at interspherulitic boundaries support this contention. The thin-section electron micrographs indicated that the spherulites were composed of radiating lamellae approximately 95 A. thick. After drawing, the lamellae were preferentially oriented both parallel and perpendicular to the draw direction. Lamellae parallel to draw had thinned to approximately 70 A. while lamellae perpendicular to the draw had apparently thickened to 150 A. .Three low-angle x-ray diffraction patterns yielded quantitative agreement with the electron-micrograph data. The pattern from the undrawn nylon was a diffuse ring corresponding to a 95 A. spacing. On the drawn specimen, with the beam parallel to draw, a ring corresponding to the 150 A. spacing was obtained, while with the beam perpendicular to draw two arcs were recorded a t spacings of 70 and 150 A. The drawing was done at room temperature and proceeded by neck formation and propagation, yielding a 4: 1 draw ratio.

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

“…Occasionally there are some indications of fibrous features within the electron micrographs (see Fig. 3), but unlike Hess et al [28], Crystal and Hansen [27], Prevorsek et al [16,29], and Geigenfeind and Owen [30] we cannot obtain clear evidence for a microfibrillar structure from our investigations. The appearance of a structure similar to that of the cold-drawn bristles was revealed in commercial nylon 6 fibres (Fig.…”

“…Furthermore, concerning the morphological characteristics of drawn material, attempts have been made using nylon 6 and nylon 66 in particular, to reveal the crystalline-amorphous microstructure by electron microscopy (EM). Rusnock and Hansen [26] and Crystal and Hansen [27] reproduced deformed spherulites of nylon 66 bristles by ultra-thin sections, which were stained with phosphotungstic acid (PTA). Previously, in a similar way Hess et al [28] had identified a structural periodicity within dispersed fibrils of commercial nylon 6 filaments.…”

The electron microscope characterization of the fine structure of nylon 6: I. The supermolecular structure in melt-cast, isotropic bulk material

“…Lamellar sheaves in nylon 6 have been well established for the crystallization from solution [11,[28][29][30][31]. Figure 5 shows a sheaf in a stained thin film with the constituent crystalline lamellae (having thicknesses of approximately 4.5 nm) being very evident.…”

“…Concerning other crystalline polymers, staining techniques have rarely been used up to now (see [7]). K 75 Phosphotungstic acid (PTA) which is well known for the negative staining of proteins, seems to be a suitable reagent for all polyamids according to the early investigations by Hess et al [8] on dispersed fibrils from nylon 6 fibres, by Spit [9,10] on solutiongrown nylon 6 films, and by Crystal and Hansen [11] on sections from nylon 66 bulk material. For investigations on the bulk it proved, however, to be very difficult in general to combine the requirements of high efficiency staining with appropriate sectioning properties of the material so as to produce suitable ultrathin sections.…”

Fibrous Structure Formation in Cold-Drawing of Polyethylene

“…More recently, extensive small-angle x-ray scattering observations on drawn. polyethylene and polypropylene have been reported by Corneliussen and I'eterlin [4,5] and Balta-Calleja and Peterlin (1,2,3]. Notably, the observed periodicity along the draw axis, as well as the variation of the periodicity with drawing temperature, were accommodated by the I'eterlin model.…”