Examination of free-volume elements in solid liquid-crystaline vectra copolyether

The content and size of free-volume elements in liquid-crystalline copolyme r Vectra were studied by the method of positron annihilation lifetime (PAL) spectroscopy. Annealing at 275 degrees C was shown to decrease the number of free volume elements by similar to 30%. Uniaxial compression to epsilon similar or equal to 40% leads to a marked increase (up to 60%) in the numbe r of free-volume elements. The pattern of compression-induced changes in th e number and size distributions of free-volume elements was characterized u sing the CONTIN computer program. Methods of thermostimulated luminescence (TSL) and differential scanning calorimetry (DSC) were used to study specif ic structural features of the samples differing by the conditions of prepar ation and treatment. The TSL and DSC data show a correlation:between the pr ofiles of the corresponding curves and the defectness of samples as charact erized by PAL spectroscopy: similarly to glassy polymers, Vectra LC polymer stores energy during deformation. As evidenced by the PAL measurements, th e defects with dimensions of about a few angstroms serve as energy carriers .