THERMOMECHANICAL ANALYSIS OF A SEGMENTED RIGID-ROD POLYIMIDE FILM

Thermomechanical analysis making use of an extension probe has been applied to characterize a series of organo-soluble segmented rigid-rod polyimide thin films. The polyimide discussed in this paper was synthesized from 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (PFMB). The polymerization was performed in refluxing m-cresol via a one-step process in which the poly(amic acids) were not isolated. The glass transition temperature (T(g)) and the linear coefficient of thermal expansion (CTE) of 6FDA-PFMB along the film surface direction are studied at different applied tensile stresses. By extrapolation to zero stress, a T(g) of 322-degrees-C and a CTE of 4.94 x 10(-5)-degrees-C-1 are obtained.