Determination of the orientation of mica in composites

Abstract A wide angle x‐ray diffraction technique has been used to determine the orientation of mica flakes in composites. The mica used was a fine grade Phlogopite, and the polymers were polystyrene, polycarbonate and poly(vinyl chloride). Composite samples of varying mica contents and orientations were prepared. The x‐ray method can give the orientation distribution function of mica flakes across and parallel to the surface of the sample. From this function, an average orientation parameter was calculated. The results show that there is no orientation of mica across the surface of the sample (the x‐ray beam is normal to the surface), but that there is a strong orientation in a direction parallel to this surface, the average orientation parameter being strongly dependent upon the particle size of mica and mode of preparation.