The structural mechanics of fibers

The “traditional” assumed structures of fibers, such as the fringed micelle and fringed fibril forms, regard the fiber as made up of a mixture of crystalline and noncrystalline regions. This view has been subject to considerable criticism in recent years, but it does, nevertheless, remain the most effective basis for describing many fiber properties. This paper attempts to show how the traditional forms can be modified, for instance by the introduction of chain folding, so that they are entirely compatible with current views on polymer crystallization. An overall picture of fiber structure is presented showing how various extreme forms–including continuous crystalline, paracrystalline, and amorphous structures as well as the two-component forms–can be used to define the boundaries of a wide range of intermediate forms which are likely to occur in practice. The major decision in interpreting fiber properties is the choice of which extreme model–necessarily extreme in order to be susceptible to definition and analysis–is the most useful when studying a particular aspect of the behavior of a particular fiber. The mechanical properties, of wool, plant fibers, rayon, and synthetic fibers are discussed.