SU1413493A1 - Method of determining thin structural changes extended polymers - Google Patents

Abstract

The invention relates to radiographic methods for the study of polymeric substances. The goal is the innovation of sensitivity and expressiveness of the method. An x-ray three-block interferometer is used to study the supramolecular structure of the polymers. Between the mirror and analyzing blocks of the interferometer, a fuzzy polymer film is placed in two positions, at which the axis of expansion lies in the diffraction plane or perpendicular to it. From the obtained X-ray moire patterns, local densities are calculated. From the density ratio, the relative displacements of adjacent crystalline or amorphous regions along or across the direction of stretch are determined. 2 Il. F cl

Description

00

four

;about

with

The invention relates to x-ray methods for the study of polymeric substances and moA (can be used to determine the structural features of stretched polymers.

The purpose of the invention is to increase the sensitivity and expressivity of the method.

FIG. Figures 1 and 2 show the X-ray optical scheme of the proposed method.

In the drawings, M, A - mirror and analyzing blocks. P — sample — stretched polymer film, X — X-ray beam, F — screen or film, O — stretching axis.

The method is carried out as follows.

The X-ray beam, the pad on the first crystal block at the Bragg angle, splits into two beams - passing and diffracted, which are diffracted in the second block M and folded at the input surface of the block A, forming an interference pattern - moire patterns on screen F. Place on the way One of the diffracted stretched film bundles leads to a displacement of moire bands. Measuring the offset, find b - the decrement of the refractive index of X-rays by the formula

where / and / o are the distances between the moire bands obtained from the interferometer without a sample and with the sample, respectively;

D is the sample thickness;

A, is the wavelength of the incident x-ray radiation;

bo is the air refractive index decrement.

After that, pi and p2 are determined by the formula, 67-10 - | -j, where L, Z is the atomic weight and the total number of electrons in the atom.

The ratio of the obtained densities is inversely proportional to the intercrystalline distances along and across the axis of stretching of the film, since the irradiated volumes along the beam both in the first and in the second case are equal to each other (the geometrical dimensions of the beam in both cases are identical):

V, V2

yVimKp + / VimaM yV2mKp + / V2 / zaM

PI

P2

five

where N and NZ are the number of crystalline and amorphous regions in the irradiated region along and across the stretching axis, respectively;

tkr and there are the masses of single crystalline and amorphous regions, respectively;

p1 and p2 are average densities along and across the stretching axis.

0 Considering the fact that intercrystalline distances, where, 2; / - length of the irradiated film, we obtain (- Thus, by determining the ratio of densities in two directions, one can find how many times the crystallites are located along the stretching axis farther than the crystallites in the direction perpendicular to this axis.

Example. The polychloroprene film was stretched by 300% and placed between blocks 0 of the three-block interferometer, as shown in FIG. 1 and 2. The film thickness before stretching is 600 microns. Radiation of C and Ca Exposure 1 hour. Mode - 30 kV, 15 mA. The ratio for 300% polychloroprene was 1.84. 5 The accuracy of determining the density of the proposed method is 10 g / cm

Claims (1)

Invention Formula  A method for determining fine structural changes in stretched polymers, which consists in directing an x-ray beam to the stretched polymer film and recording a diffraction pattern, characterized in that, in order to increase the sensitivity and expressivity of the method, the stretched polymer film is placed in a three-block an x-ray interferometer onto which an x-ray beam is directed at the Bragg angle, with 0 the film is placed between the mirror and analyzing blocks of the interferometer perpendicular to the reflected beam, the moire patterns for two positions of the film are taken, at which the stretch axis lies in the diffraction plane or perpendicular to it, according to the moire pattern obtained for each of the positions of the film the local density is calculated and the relative displacements of neighboring crystal or amorphous regions along and across the direction of stretch are determined from the ratio of the densities. five d about F Mi FIG. one