Small angle X‐ray scattering pole figures of semicrystalline polymers obtained by synchrotron radiation

Abstract

A goniometer for measuring small angle X‐ray scattering pole figures by using synchrotron radiation has been constructed. In order to obtain the scattering in a large range of scattering angles, position‐sensitive detectors (Gabriel counter and vidicon system) are applied. The integrated intensity as well as the position and the half width of the maximum are determined as functions of the angle between the incident beam and the normal to the film surface of the sample. The time necessary to determine a pole figure was approximately 3 hours. Samples of poly(ethylene terephthalate) were drawn under different conditions: uniaxially and biaxially at 92°C under homogeneous deformation, and uniaxially at 40°C by necking. The influence of the drawing conditions on the orientation of the crystal lamellae was determined. The results of the small angle scattering are compared with pole figures obtained by wide angle scattering. In addition some results with polypropylene were obtained. The small angle X‐ray scattering is strongly affected by the limited size of the crystals and by the incomplete regular arrangement of the crystals. This gives rise to difficulties in the interpretation of the results. The problem will be discussed.

Stress-oscillation behaviour of semi-crystalline polymers: the case of poly(butylene succinate)

“…The sharp meridional spots indicate that throughout the SO bands, the lamellar morphology (or lamellar stacking) is now well oriented in the deformation direction. 43,44 The 2D WAXS also shows the Bragg rings have now concentrated into sharper arcs and spots on the equator, again confirming a highly oriented crystalline morphology. Returning to the 2D SAXS equatorial scattering around the beam stop; the size and intensity changes through the SO bands.…”

The formation of a nanohybrid shish-kebab (NHSK) structure in melt-processed composites of poly(ethylene terephthalate) (PET) and multi-walled carbon nanotubes (MWCNTs)

“…SAXS patterns of the extruded samples at 30 ºC prior to any further crystallization are given in Figure 1, including schematics of the associated polymer crystalline or amorphous structure. [12,42,48,49] The SAXS pattern for neat PET shows only diffuse scattering around the central beam stop, thus indicating no crystalline structure prevails from the extrusion process and the polymer is amorphous. In comparison, the PET1% composite shows increased scattering around the beam stop seen as a ring of intensity.…”

Crystallisation behaviour of composites of HDPE and MWCNTs: The effect of nanotube dispersion, orientation and polymer deformation

“…The SAXS pattern for neat HDPE shows an isotropic ring of intensity which is indicative of a randomly oriented crystalline lamellar structure [77]. Similarly, the WAXS pattern shows several rings, the two strongest are the (110) and (200) reflections of the orthorhombic unit cell of HDPE [78].…”