Calculation of limiting young's moduli of rigid-rod polymers including poly-p-phenylene benzobisthiazole (PBT)

Abstract

Limiting Young's modulus along the chain direction has been calculated based on the lattice dynamical theory for the several rigid-rod polymers: 371.0 GPa for poly-p-phenylene benzobisthiazole (PBT) (macroscopic modulus ca. 250 GPa), 275.1GPa for poly-p-phenylene, 588.3GPa for poly-pbenzobisthiazole, and 505.3GPa for poly-p-phenylene pyromellitimide (macroscopic modulus ca. 130GPa). The difference in the Young's modulus among these polymers has been discussed based on the atomic displacements and potential energy distribution calculated for the tensile deformation of the chains. Tentative band assignments of the infrared and Raman spectra of PBT were made in order to check the propriety of the force field used in the above calculation.