The purpose of this work was to show in a conclusive way the c!b phase transformation induced by uniaxial stretching in poly(vinylidene fluoride). Poly(vinylidene fluoride) films were melted and crystallized at 163 C for 36 h. Under these conditions, a mixture of a and c phases was formed, with a predominance of the latter. These films were uniaxially stretched at 130 C at a draw ratio of 4. Fourier transform infrared and differential scanning calorimetry analyses showed a c!b phase transition in the solid state, whereas orientation of the a phase without any transition was observed. Optical microscopy analysis permitted the observation of the transformation of spherulitic structures into oriented lamellae during stretching.

To turn the advantage of energy measurement in x-ray transmission diagnosis into practice, we propose a novel detector for the estimation of x-ray energy distribution. This detector consists of several segment detectors arrayed in the direction of x-ray incidence. Each segment detector measures x-rays as current. With unfolding measured currents, the x-ray energy distribution is obtained. The practical application of this detector was verified by estimating the iodine thickness in an acryl phantom.

To turn the advantage of energy measurement in x-ray transmission diagnosis into practice, we propose a novel detector for the estimation of x-ray energy distribution. This detector consists of several segment detectors arrayed in the direction of x-ray incidence. Each segment detector measures x-rays as current. With unfolding measured currents, the x-ray energy distribution is obtained. The practical application of this detector was verified by estimating the iodine thickness in an acryl phantom.

The computed tomography (CT) values obtained by the energy subtraction method with a transXend detector, which measured X-rays as current and gave the corresponding X-ray energy information, show the disadvantage that the CT values are dependent on the thickness of a homogeneous phantom. In order to obtain constant CT values for a uniform material, a new unfolding method is proposed using variable response functions of the transXend detector according to the X-ray path length in the phantom. The CT values measured using the new unfolding method are discussed with respect to the energy range used in the unfolding process, the number of segment detectors, and the substrate of the segment detectors.

In conventional X-ray computed tomography (CT), X-rays are measured as electric current. Materials inside a subject are described by the linear attenuation coefficients averaged by the energy spectrum of the X-rays. A CT image cannot distinguish materials such as iodine and calcium, because the linear attenuation coefficient is not inherent to a material, but the product of X-ray mass attenuation coefficient and the density of the material. Materials such as iodine and calcium can be distinguished using an energy-resolved CT technique, with a current-mode detector system, using segment detectors aligned in the direction of X-ray incidence: the energy-resolved CT images are reconstructed by the X-rays with the energy of interest, by unfolding electric currents measured by the segment detectors.

SynopsisSome preparations of xylan in the form of transparent membrane or amorphous powdw prepared from deciduous woods such as beech and birch show a number of Debye-Scherrer rings a t the irradiation with x-ray. Of special interest from the crystallographic standpoint is the diffraction pattern of the membrane, which shows an indication of a fiber diagram with the beam parallel to the surface, and this is more obvious when the membrane is stretched to an appropriate extent by rolling. The diagram can be neatly interpreted on the basis of an end surface-centered rhambic cell whose two axes of the base plane have exactly the ratio of G: 1, within the limit of experimental error. It is assumed that the cell has a trigonal or hexagonal symmetry. The observed reflections are indexed on the base of orthohexagonal unit cell, whose postulated three axes are a = 9.16 A., b = d a . , and c = 15.5 A. (fiber axis). The crystalline lattice of xylan is susceptible to mechanical treatment, heat, and moisture. The crystallinity depends greatly upon the uronic acid content. The diffraction pattern becomes less distinct and the interplanar spacings are enlarged with increasing uronic acid content, until at last the pattern diffuses into a single halo.

No abstract

In this report, the orientation mode in the film plane and the relationship between the molecular structure and the surface state are discussed for the uniaxially stretched and simultaneously biaxially stretched poly(ethylene terephthalate) films prepared by wet-process.Sample films used in this study were the T-die extruded film with 140 It thickness. The uniaxial and the biaxial stretching of the films were done using a film-stretcher in a recirculating hot glycerin bath.The following results were obtained:(1) The crystalline orientation of simultaneously biaxially stretched films was random in the plane, however, that of two-way successively biaxially stretched films was selective to some extent.(2) The selective planar orientation parameter of the simultaneously biaxally stretched films was larger as compared with that of the uniaxially under constant width stretched films , in the machine direction and same stretch ratio.(3) The tautness-parameter of molecular chain in the simultaneously biaxially stretched films was smaller than in the two-way successively biaxially stretched films , but this tendency was reversed by the heat treatment under the fixed length.(4) The size of crystallite in the simultaneously biaxially stretched films was nearly equal in both the machine and the transverse directions.(5) On the electromicroscopic observation, the simultaneously biaxially stretched films with lower stretch ratio showed no charactristic surface structure , however, these films with higher stretch ratio represented the fibril-like structure.The molecular chain is locally uniaxially oriented in various directions in the plane , but the orientation is totally cancelled by averaging in the thickness direction which is due to the multi layer structure.That is, the simultaneously biaxially stretched films shows the uniplanar orientation.