X‐ray determination of crystallinity in poly(ethylene terephthalate)

Three recently published x‐ray methods for determining the crystallinity of poly(ethylene terephthalate) are discussed and compared with density and infrared methods. The effect of crystallite size is shown to account for most of the disagreement among the several methods. A short method of estimating crystallinity from x‐ray diffraction, suitable for counting techniques and requiring only two measurements, is presented and compared with the density method.