Thermal expansion of oriented liquid crystal copolyesters

Abstract

Abstract The axial thermal expansion coefficients of a series of highly oriented thermotropic liquid crystal copolyesters with random phenylene‐naphthalene main‐chain sequences are reported. In common with many other highly oriented polymers the values are negative. Generally, there are two transitions in the slope of the expansion‐temperature curves. The positions of these transitions are correlated with high activation energy relaxations in the mechanical spectra. Comparison of the thermal expansion properties determined by x‐ray and macroscopic techniques on two of the samples reveals little difference between the bulk material and a unit with a segmental length of ten monomers.