Small‐angle x‐ray scattering by nylon 6

Abstract

SynopsisSmall-angle x-ray scattering (SAXS) of isotropic or uniaxially oriented nylon 6 was investigated as a function of thermal and mechanical history. In addition to the peak position and linewidth of the SAXS maximum, the integrated SAXS intensity was measured. It was found that the radial intensity distributions of isotropic or arced patterns are controlled to some extent by the small width of the semicrystalline macrolattice, rendering the conventional long period and line shape analysis inapplicable to these patterns. A two-dimensional analysis is possible with well-oriented fibers; the major structural changes which are seen in fibers after annealing above 190°C are associated with melting and recrystallization. Extensive cold drawing and subsequent annealing cause rather modest (ca. -30%) changes in the integrated SAXS intensity. These effects are consistent with the generation of homogeneous interfibrillar regions during the latter stages of plastic deformation. On annealing a quenched film on nylon 6, the transformation of the crystals from a pseudohexagonal to a monoclinic habit occurs above 170°C.

Hydrogen bonding, mobility, and structural transitions in aliphatic polyamides

“…Consider, for instance, the rapid decrease in the tensile strength and increase in the shrinkage in PA-6 fibers annealed above 170 8C, and the maximum in the shrinkage stresses at $160 8C (in addition to the one at 90 8C). 78 These are associated with the increases in the density and crystallinity, the increases in the size, orientation, and density of the crystals, and the increases in the long period and the intensity of the corresponding lamellar peak (lamellar intensity). [84][85][86][87][88] However, these changes cannot be quantitatively predicted from the available structural models and the known crystallization behavior.…”

“…These changes begin to occur at 160-190 8C in PA-6. 78,85,[87][88][89][90][91] This could be due to crystalline chain relaxation that also accounts for premelting structural transitions, 87 the Brill transition being the most widely known among these. …”

“…6(b)]. 72,[77][78][79][80][81][82] Under stress, as the lamellae move apart, these lamellae rotate so that the lamellar surface normal aligns itself along the fiber axis, giving rise to two-point patterns. 72,82 This rearrangement is mostly reversible below the yield point of the polymer.…”

SAXS-Fiber Computer Tomography. Method Enhancement and Analysis of Microfibrillar-Reinforced Composite Precursors from PEBA and PET

“…Such an effect has frequently been found after a drawing of polymer materials. [43][44][45][46][47][48][49] MFC7 is very close to local fiber symmetry. Thus, application of XSF-CT results in almost perfect reconstruction of the nanostructure.…”

Small-angle X-ray data processing for planar multilayered structures. 2. Experimental determination of the parameters for retinal photoreceptors and sarcoplasmic reticulum membranes

“…An integration of the transverse layer-line profile provides the total disc intensity and this method has been applied to polymers (Matyi & Crist, 1978). In the present X-ray experiments using pinhole (limited slit) collimation, the X-ray beam contributes noticeably to the broadening of the layerline profiles and it can be shown that knowledge of the correction factor and the size of the X-ray beam is needed before the Fourier-transform values can be obtained (Crist & Worthington, 1980).…”