A NOVEL POLYMER FIBER DIFFRACTOMETER, BASED ON A SCANNING X-RAY-SENSITIVE CHARGE-COUPLED-DEVICE

This paper describes the development of a novel X-ray diffractometer, designed for the study of highly uniaxially oriented polymer fibres. T he system is designed around a commercial X-ray-sensitive video camera , which is mounted on a three-circle goniometer. The active element in the X-ray camera is a charge-coupled device (CCD). The data-collectio n procedure consists of the combination of several diffraction images, obtained with the detector centred at different points in reciprocal space, to construct a composite diffraction pattern representing a lin earized section through the symmetry axis of cylindrically averaged re ciprocal space. By the combination of several images in this way, it i s possible to overcome the traditional problem in fibre photography of information loss, caused by the Ewald-sphere curvature, close to the reciprocal fibre axis. Methods for optimizing the performance of the C CD detector, in terms of both its resolution and sensitivity, are disc ussed, and the data gathering and processing system is described in so me detail. The operation of the system is demonstrated using samples o f liquid-crystalline and conventional synthetic polymeric fibres.