Positron Annihilation Lifetime in situ Study of Deformed Polyolefin Elastomers

The positron annihilation lifetime spectroscopy was used to investigate the free volume hole size of ethylene octane copolymers as a function of deformation in the range from 0 to 110% in steps of 10%. For each degree of deformation a series of 5-6 positron annihilation lifetime spectra was collected in situ. All spectra of a given series were analysed simultaneously. They were resolved into three exponential components, of lifetimes parameters τ$\text{}_{i}$ and intensities I$\text{}_{i}$. The variations of τ$\text{}_{3}$ reflect three deformation regions, the elastic range, strain softening range, and plastic region.