Effect of a thermotropic liquid crystalline polymer on the physical ageingof PET

In this work the effect of the presence of a thermotropic liquid crystallin e polymer (TLCP) on the physical ageing of poly(ethylene terephthalate) (PE T) was investigated. Physical ageing of PET and its blends with a TLCP was carried out by annealing the samples at 60 degrees C for several ageing tim es. Structural relaxation has been revealed by DSC through the analysis of position and magnitude of the endothermic peak superposed on the glass tran sition. It was found that the peak increases and shifts towards higher temp eratures as the annealing time increases for all materials analysed. With r espect to the PET matrix, blends submitted to physical ageing show an incre ase in the ageing rate by a percentage that increase with the amount of TLC P Moreover, increasing the fraction of liquid crystalline component, a cont inuos decrease of the cord crystallisation temperature has been also observ ed.