Temperature dependence of the elastic modulus of the crystalline regions of poly(p-phenylene benzobisthiazole)

Abstract

Temperature dependence of the elastic modulus El of the crystalline regions of poly(p-phenylene benzobisthiazole) (PBZT) in the direction parallel to the chain axis was investigated by X-ray diffraction over a temperature range from −180 to 400°C. The El value of PBZT was 372GPa at room temperature, which was the highest El value ever investigated. This value coincided with that reported by Lenhert and Adams (395GPa) [Lenhert PG, Adams WW, Mat. Res. Soc. Symp. Proc. 1989; 134: 329] within experimental error. The axial chain thermal expansion coefficient was constant at −2.9×10−6K−1 from 20 to 445°C, and correspondingly the El value remained unchanged up to 400°C. Moreover, the El value at −185°C also coincided with that at room temperature. It is considered that the deformation mechanism remains unchanged over a wide temperature range and the skeletal conformation of PBZT in the crystalline regions is stable against the heat.