engleski

ESR - Spin Probe Method in Studying Crosslinked Elastomers: an Effect of the Probe Incorporation Temperature

The natural rubber (NR) latex containing 30% of dry matter was exposed to the high energy irradiation. 60Co was used as γ -irradiation source. Total irradiation doses varied from 0 kGy (for the nonirradiated sample) to 300 kGy. NR films with the thickness of about 1 mm were prepared by removal of the liquid phase (evaporation) at room temperature. 2, 2, 6, 6-tetramethyl-piperidine-1-oxyl free radical, used as the spin probe, was incorporated into the NR matrix by diffusion. The NR samples were swollen in the toluene probe solution at different temperatures. The swelling temperatures, kept constant for the each series of samples, were varied from 4º C to 35º C. In the same time, the solvent slowly evaporated. Finally, the samples were annealed under the vacuum in order to remove the residual solvent. ESR spectra show significant influence of the probe incorporation temperature on the spectral shape and linewidths. More precisely, the amount of the broad component in a composite ESR spectrum increases with the increasing probe incorporation temperature.

electron spin resonance ; spin probe ; probe incorporation temperature ; linewidth

nije evidentirano