Polymers, Oriented State of

a state of bodies composed of linear polymers in which the axes of the long chain molecules are oriented predominantly in certain directions. The simplest and most frequently encountered type of orientation is uniaxial orientation (for example, in fibers).

There are two major methods for producing uniaxially oriented polymer bodies: (1) orientational stretching, in which a body gripped at both ends is stretched, and the degree of elongation may range from several tenths of a percent to thousands of percent, and (2) the production of a polymer under conditions such that a body with oriented structure is formed directly, for example, in solid-phase polymerization when the monomer is in the form of a single crystal or in the polymerization of a liquid polar monomer in a constant electric field.

Uniaxially oriented polymers are characterized by high tensile strength combined with the capacity for reversible elongation in the direction of the axis of orientation. These properties are produced mainly in crystallizing polymers such as olefin polymers, which are used as fibers and films.

In addition to “artificially” oriented polymers, uniaxially oriented biological polymer materials (plant fibers, cobwebs, silk threads, hair, tendons, and muscle fiber tissue are very common.