The relationships between tensile properties and macromolecular orientation of a thermotropic copolyester of hydroxybenzoic acid and hydroxynaphthoic acid are investigated with respect to their differing processing histories. A correlation between modulus and orientation is described using simplified aggregate models and is shown to be independent of the method of sample preparation. Tensile strength also depends on the sample preparation conditions of extrusion temperature, deformation rate and the method of orientation. Tensile yield behaviour is predominant in samples of low orientation. Yielding can be characterized by a single strain level of 0.7%, similar in magnitude to values reported for lyotropic liquid crystalline polymers.
Посилання на статтю:
Processing/property relationships of a thermotropic copolyester: 2. Correlations between tensile properties and orientation / Douglas E. Turek* and George P. Simon // Polymer. – 1993. – Vol 34. – P. 2763-2768.