An instrument for the collection of simultaneous small and wide angle x-ray scattering and stress-strain data during deformation of polymers at high strain rates using synchrotron radiation sources

A fully integrated system has been developed which allows the study of the deformation of synthetic polymers by simultaneous small- and wide-angle x-ray scattering (SAXS/WAXS) and stress-strain techniques at synchrotron radiation sources. Two-dimensional x-ray data collection is achieved via two charge coupled device based area detectors which provide video signal outputs. A video extensometer provides sample strain and cross-section data during deformation. All three video signals are processed by a powerful Synoptics i860 processor based video framegrabber, with no loss of data. With this data collection strategy a temporal resolution of 40 ms is possible. In order to study the mechanical yield of the sample, a bridge-type strain gauge is used which reveals the sample loading. An electronic trigger mechanism provides accurate synchronization of the x-ray data, sample video data, sample loading information and controls the onset of deformation. Two experiments are highlighted showing the drawing of polyethylene at an overall rate of approximate to 10 s(-1). By analysis of the sample video data it is possible to correlate the SAXS and WAXS data with specific points upon the true stress-strain curve. This novel system is shown to be a useful tool for the investigation of the deformation of polymers at rates that are relevant to industrial processing. (C) 1999 American Institute of Physics. [S0034-6748(99)00210-5].