Microscopically viewed relationship between structure and mechanical property of crystalline polymers: An important guiding principle for the development of super fibers

Abstract

The crystalline phase of polymer substance may be assumed as an idel state for the study of ultimate mechanical property of this polymer. The historical development in the study of structure-property relationship of polymer crystals has been reviewed by focusing on the crystallite modulus along the chain axis, the anisotropy in the lateral plane perpendicular to the chain axis, and the strength. This information is quite important as a guiding principle of the development of fibers with ultrahigh modulus and ultrahigh strength. In other words, the history of the development of these super fibers has been a challenge for approaching the goal of ultimate mechanical property. The experimental and theoretical methods to estimate the ultimate mechanical property of polymer crystals have been reviewed in Sects. 6.2, 6.3, 6.4, and 6.5. In the experimental approach, the X-ray diffraction peak shift and Raman band shift caused by the application of tensile stress are measured to detect the mechanical deformation of crystalline region, but the data analysis must be performed by taking the heterogeneous distribution into account. The quantum mechanical prediction of the ultimate strength of polymer chain has been reviewed in Sect. 6.6. The factors governing the strength of bulk polymer sample have been discussed concretely.