Absolute measurements of X‐ray scattering at low angles in crystalline polymers

It is generally taken for granted that the low angle X‐ray scattering exhibited by crystalline polymers is associated with the density fluctuations due to the succession of crystalline and amorphous regions in colloidal dimensions. If this is true – and only then – the diffraction pattern may be interpretated in terms of shape and size of these regions. Since it has previously been shown through absolute measurements of the intensity scattered at small angles that in most native and artificial cellulose fibers the major part of the intensity is diffracted by microvoids rather than by the crystalline amorphous structure and thus, that their diffraction pattern reflects the size and shape of the voids rather than that of the crystallites, it was of interest to examine other polymers using the same methods. The present paper presents absolute measurements of low angle diffraction in polyethylene, polyethylene terephthalate, Nylon 6 and polyformaldehyde. The observed intensities of scattering were found to conform with the order of magnitude calculated for the crystalline‐amorphous structure. No indication of a contribution of micro‐voids to the scattering was observed.