Study of polystyrene–polyethylene IPN system by the spin probe method

The spin probe method has been used to study the structure and molecular mobility of PS–PE IPN with various ratios of PS:PE. The dependence of the correlation times of motion of the spin probe and the linwidths of the EPR spectra on the composition of the IPN system and its thermal processing has been studied. The results imply that rotation correlation time of the probe is highest at the ratio PS:PE 1.5:0.5 and lowest at the ratio 0.75:1.25. The value of τ decreases with decreasing content of PS. At the transition from the ratio PS:PE 1.25:0.75 to 1:1 τ decreases sharply to a value close to the correlation time of PE. In the temperature range 173–373 K there are two domains which differ in molecular mobility. At temperatures above T_m of PE, heterogeneity is observed for samples with ratio of PE 1 or 0.75. Annealing at 473 K makes the samples homogeneous, which means that mixing of the chains of both polymers is observed in the interpenetrating regions.