Polymers and fibers

SAXS can complement wide angle X-ray scattering (WAXS) X-ray diffraction measurements for a better understanding of the relationship of processing to material properties. The angular region examined in a SAXS experiment is typically from several hundredths of a degree to a few degrees 2θ. This small-angle region contains information about structures having large d-spacings (up to ~600 Å with pinhole optics).

Small-angle scattering pattern of a polymer sheet cross-section
Figure 1: Small-angle scattering pattern of a polymer sheet cross-section showing a hexagonal columnar structure. This pattern can yield the arrangement of a column structure, its diameter, and the distances between columns.

Small-angle X-ray scattering measurements can provide the following information:
  • Lamellar repeat distance: The distance from the center of one bilayer to the center of its neighbor, which includes the thickness of associated water layers.
  • Radius of gyration: The first moment of the scattering center distribution function.
  • Particle size and shape: from Guinier's and Porod's Laws.
  • Large-scale structure and long-range order: distances between similar structures.

This technique has been used extensively in polymer industries to characterize the morphological effects of drawing, rolling, and annealing on mechanical properties.

Small-angle scattering pattern of a single polypropylene fiber

Figure 2: Small-angle scattering pattern of a single polypropylene fiber.
The fiber is oriented vertically.

Samples for small-angle X-ray scattering include:
  • Polymers and fibers (e.g. textile yarns)
  • Wood products
  • Detergents and surfactants
  • Lipids and membranes
  • Liquid crystals
  • Glasses
  • Catalysts

The S-MAX3000 pinhole SAXS camera design is available with a choice of conventional or high brilliance X-ray sources. A 3-meter, fully evacuated camera length provides both high intensity and high resolution. Coupled with a fully integrated 2-dimensional multi-wire proportional counter, the system is capable of making highly sensitive measurements from both isotropic and anisotropic materials. A wide range of sample stage attachments provide maximum flexibility in controlling environmental sample conditions during measurement. Read more...