Structure of the amorphous phase in oriented flexible-chain polymers

Abstract

The effect of the cross-section of crystals and thickness of the amorphous phase in fibre-forming oriented polymers on transfer chains, kinks, and "cilia" in Both oriented and unoriented crystalline polymers consist of alternating crystalline and amorphous regions. The molecules coming out in one crystalline region can terminate in an amorphous region, forming kinks (pos. 2) and can pass into a neighboring crystalline region, forming transfer chains (pos. 3). As previously established in [1,2], the mechanical properties of polymers (for example, the modulus of elasticity and strength of fibres) are greatly determined by the proportion of transfer chains --the higher it is, the higher the indexes of these properties. It can be intuitively predicted that when the cross-sections of the crystals and the thickness of the amorphous region change, the proportion of transfer chains should also change. However, it is somewhat difficult to verify this with the usual experimental methods. We used the method of the computer experiment in a cubic lattice based on the widely used Monte Carlo method for this purpose [3][4][5][6]. It was hypothesized that the cross-section of the crystals was in the shape of a square, and the polymer segments in both the crystalline and in the amorphous phases can only be positioned along the sides of the cubic lattice cells.We will select a rectangular system of coordinates and place the origin of the coordinates in the center of the end of one of the crystals. We will position axis z along the axis of the molecules in the crystal in the direction of the nearest amorphous phase and axes x and y along the sides of the cubic lattice cell perpendicular to the side faces of the crystal (Fig. 1).The segments of the molecules can come out into the amorphous region from any cubic lattice site on the end face of the crystal. If the site examined is not on the side of the crystal, then the first amorphous segment can only be positioned in one way --along axis z in the direction of its enlargement, since the neighboring segments will interfere in positioning it in other directions. The second amorphous segment can be positioned in five different ways: four ways --perpendicular to axis z (one along axes x and y and one opposite them) and one way --along axis z. This segment cannot be positioned opposite axis z, since the first segment has already been placed there.If the second segment occupies a position along axis z, then the third segment will be positioned similar to the second segment. If the second segment is located along axisx, for example, then the third segment can be positioned in the following five ways: one along axisx, one along axis y, one opposite axisy, one along axis z, and one opposite axis z. The third segment cain be positioned opposite axis x, since the second segment is located there. If the third segment is positioned opposite axis 2000.Moscow State Textile University.