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The effect on PTFE of crystallization conditions and subsequent tensile deformation have been examined by Fourier analysis of the shapes of diffraction peaks. Crystal perfection increases with decreasing rate of cooling from the melt. During deformation, the crystallite size is reduced drastically in the range of strain from 35 to 185%. The microstrains are not altered over this range, implying crystal breakup rather than distortion within crystallites. It is in this range that previous studies with the same specimens have indicate a sharp transition in texture. The fact that root-mean-square (rms) microstrains increase due to elongation suggests that the crystalline regions not only break up but that they are also deforming plastically. Electron microscopic investigation indicate that the striation spacing on crystals in the fracture faces is much smaller than the crystallite size measured with x-rays; thus the striations do not represent alternating crystalline and amorphous regions.

X-ray methods have been used to determine the preferred orientation of crystallites in PTFE sheets stretched varying amounts in the trigonal phase at room temperature. Spherical harmonic analysis of the x-ray data was carried out to obtain inverse pole figures. At high elongations results show preferential alignment of the c axis (chain direction) with the extension axis. At lower elongations there is also a tendency for (h0h̄l) poles to be aligned with the extension axis. The results at low extension are interpreted as being caused by slip occurring on {1120} planes along the tangent to the helix formed by the PTFE molecule. Experiments carried out in the hexagonal phase above 30°C, and in the triclinic phase below 19°C support these conclusions.

In recent years, significant advances have been made in methods for analyzing texture in polycrystalline materials. These spherical‐harmonic analysis methods are emphasized in this short review. Applications to metals and plastics are discussed, including methods of obtaining polycrystal properties from orientation data and single‐crystal properties, prediction of texture formation in metals, and deduction of single‐crystal deformation mechanisms from polycrystal texture formation in polymers.