Free-volume evolution in the system polycarbonate–polycaprolaptone studied by positron annihilation spectroscopy

Positron annihilation spectroscopy (PAS) can measure the free-volume properties in polymeric materials. In this paper PAS has been used to follow the free-volume evolution in several samples of polycarbonate (PC) with different contents of polycaprolaptone (PCL) and different annealing times at 418 K. Results show that an increase in the content of the PCL added to the sample decreases the free-volume radius present in the PC. From the data obtained it can be observed that the free-volume radius is linearly dependent on the content of PCL in the range 0–10% of PCL. An increase in the annealing time at 418 K also produces a decrease in the free-volume radius of the samples. However, the relative variation in the free volume of the samples is much less than the change produced by the PCL.