Miscibility of a nematic liquid crystalline polymer pair

This work investigates the miscibility of two commercially important thermotropic main chain liquid crystalline polymers (LCPs), Vectra A950 and Vectra B950, using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and positron annihilation lifetime spectroscopy (PALS). Although previously reported to be either miscible or show a compositional-dependent miscibility, they are shown here to be immiscible based on DMA, DSC and PALS results. The latter technique is somewhat more novel in its use to assess miscibility, by probing the free volume of the blends and comparing this to rule-of-mixtures values of the two components.