The temperature dependence of free volume in polymethylpentene by positron annihilation

Positron lifetime measurements in polymethylpentene were performed in the temperature range 8.3-299 K. A conventional fast-slow coincidence lifetime spectrometer with plastic scintillators were used. All the measurements were made in vacuum. Additional measurements (X-ray diffraction, differential scanning calorimetry and mechanical spectroscopy) were also performed to establish properties of samples. Mean free volume radii and fractional free volume in the investigated samples were estimated from the positron lifetimes