Investigation of foamed polystyrene by positron annihilation lifetime spectroscopy


Chem. Met. Alloys 4 (2011) 81-84




Positron annihilation lifetime measurements obtained for foamed polystyrene samples of different density are presented. Two series of samples (exposed and not exposed to open air) were investigated. The dimensions of the pores were determined. The free volume was found to decrease from 137 to 104 Å3 with increasing density of the material. The largest concentration of micropores (dimensions up to ~0.7 nm), represented by the intensity of the long-lived component, was obtained for a solid (not foamed) sample.



Upper panel: delayed-coincidence spectrum obtained for solid polystyrene (HDPS). The result of the deconvolution of the spectrum into contributions of individual positron fractions to the annihilation process is shown. Lower panel: difference between the experimental spectrum and its fit expressed in units of standard deviation.



Foamed polystyrene / Positron annihilation / Micropores