Mesophases in polyethylene, polypropylene, and poly(1-butene)

A commercially available small-angle X-ray scattering camera, NanoSTAR from Bruker AXS, has been modified to optimize its use for weakly scattering solution samples. The original NanoSTAR is a pinhole camera with two Gobel mirrors for monochromating and making the beam parallel, and with a two-dimensional position-sensitive gas detector (HiSTAR) for data collection. The instrument has one integrated vacuum. It was constructed for position-resolved studies and thus has a small beam size at the sample position. In the present work, the instrumental configuration has been optimized by numerical calculations based on phase-space analysis and Monte Carlo simulations in order to obtain a higher flux. This has led to a setup in which the beam at the sample is larger and the collimation part of the instrument is longer, so that divergence of the beam is similar to that of the original camera. An extra pinhole is included after the Gobel mirrors to make the beam size well defined after the mirrors. The camera thus has genuine three-pinhole collimation. The use of electron-microscope pinholes minimizes parasitic scattering. At the University of Aarhus, the modified camera is installed on a powerful rotating-anode X-ray source (MacScience 6 kW Cu with a 0.3 × 0.3 mm effective source size). Measurements have been performed on a wide variety of weakly scattering samples, such as surfactant micelles, homopolymer solutions, block copolymer micelles, proteins etc. The data are routinely converted to absolute scale using the scattering from water as a primary standard. The standard configuration covers the range of scattering vectors from 0.01 to 0.35 A−1 with a flux of 1.7 × 107 photons s−1 for Cu Kα radiation at a generator power of 4.05 kW. The camera is easily converted to a high-resolution version covering 0.0037 to 0.22 A−1 with a loss of flux of about a factor of 10, as well as to a position-resolved version.

A flux- and background-optimized version of the NanoSTAR small-angle X-ray scattering camera for solution scattering

Structural formation of poly (ethylene terephthalate) during the induction period of crystallization: 1. Ordered structure appearing before crystal nucleation

Structural formation of poly(ethylene terephthalate) during the induction period of crystallization. 2: Kinetic analysis based on the theories of phase separation

Effect of solvent exchange on the solid structure and dissolution behavior of cellulose.

A new multipurpose X-ray small-angle scattering camera system consisting of a rotating-anode X-ray generator, a double-focusing collimator and a two-dimensional position-sensitive detector has been developed at the High-Intensity X-ray Laboratory of Kyoto University. The overall camera length is 6 m, and the sample-to-detector distance can be varied in 0.5 m increments up to 3 m to cover scattering angles ranging from 0.001 to 0.18 rad. The collimator consists of a pair of crossed-plane total-reflection mirrors of 40 cm in length. The mirrors, which are mechanically bent to form cylindrical surfaces, provide point collimation free of collimation error. General-purpose sample holders equipped with a programmable temperature controller are provided for both transmission and scattering measurements; the temperature is maintained within ± 0.1 K in the range of 223–573 K. A cryostat for measurements down to 20 K, a dynamic sample deformation apparatus, and a temperature-jump equipment are also available. The multi-wire delay-line position-sensitive proportional counter has an active area of 128 × 128 mm with a spatial resolution of 0.5 × 1.0 mm. The data acquisition is controlled by a real-time front-end processor through a CAMAC interface. The data are recorded in a dual-port histogramming memory of 32 bit × 1 Mwords, which enables direct access to the data from the main computer for real-time monitoring and analysis. The performance of the camera is demonstrated with some selected examples: diffraction patterns from carp lateral line nerve myelin and chicken-tendon collagen fibrils, a Guinier plot of the scattering from polystyrene in dilute solution, and time-resolved measurements of polypropylene during the annealing process.

N. Masaki

Papers

The 6 m Point-Focusing Small-Angle X-ray Scattering Camera at the High-Intensity X-ray Laboratory of Kyoto University