A new approach to the determination of crystallinity of polymers by X-ray diffraction

A new X-ray diffraction method for the determination of crystallinity of polymers is reported. A probability function is used to express the intensity distribution of an amorphous halo. The intensity of the halo buried under any crystalline peak can be calculated by this function. An amorphous-standard-addition method was used to determine crystallinity. A linear relationship between intensity and concentration is derived theoretically and applied to polyethylene terephthalate. No previous chemical or structural information about the polymer is necessary for this method. Very good agreement between X-ray data and density measurements were obtained. This method is rapid, practical and suitable for routine analysis.