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X-Ray Scattering in Analysis of Polymers

Polymers and Rubbers

  1. Christopher Y. Li,
  2. Bojie Wang,
  3. Stephen Z.D. Cheng

Published Online: 15 SEP 2006

DOI: 10.1002/9780470027318.a2039

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Li, C. Y., Wang, B. and Cheng, S. Z. 2006. X-Ray Scattering in Analysis of Polymers. Encyclopedia of Analytical Chemistry. .

Author Information

  1. The University of Akron, USA

Publication History

  1. Published Online: 15 SEP 2006

Abstract

It has been proved that X-rays play a very important role in the characterization of polymers. A wealth of information concerning polymer structures and morphologies are accessible by using X-ray techniques. X-ray studies in the polymer area are based on the same principle as that in studies of other materials. The present review attempts to give a short summary of the roles that X-rays play in modern polymer science.

The first three sections provide a brief introduction about the origin of X-rays, the principle of the interaction of X-rays and matter, and X-ray diffraction. Section 4 briefly describes X-ray instrumentation. In section 5, crystal unit cell and structural determination methods are discussed. The focus is on the use of uniaxially oriented polymers, as this is the most commonly used method for determination of polymer crystal structures. Crystallinity is another issue, which is specifically important to semicrystalline polymers. A short summary of the concept of crystallinity and its determination based on X-ray diffraction is discussed. Polymer liquid crystals are a new field which has been growing rapidly since the late 1970s. X-rays have again played an important role in liquid crystal phase determination. By combination of X-ray techniques with other structure and thermal property measurements, almost every polymer liquid crystal phase can be identified. Section 6 discusses the small angle X-ray scattering (SAXS) technique. The cause of X-ray scattering in the small-angle region in most polymers is due to the heterogeneous electron density distribution over distances that are large in comparison with the wavelength of the X-ray (5–100 nm). SAXS is a powerful tool in semicrystalline morphology and block copolymer phase-morphology studies. In the thin film field, X-ray diffraction at small angles is also useful in determining the film thickness and interface structure.