engleski

ESR - Spin Probe Method in Studying Natural Rubber: an Effect of the Probe Incorporation Temperature

Natural rubber (NR) latex containing 62 wt.% of solid phase was dried by evaporating the liquid phase at room temperature. 4-hydroxy-2, 2, 6, 6-tetramethyl- piperidine-1-oxyl free radical, used as the spin probe, was incorporated into the NR matrix by swelling the samples in toluene probe solution at 4 °C, 24 °C and 37 °C. The probe incorporation temperatures were constant for each set of samples. When the solvent was slowly removed, all samples were annealed at 60 °C during 72 hours. Composite ESR spectra observed in the vicinity of T5mT show a significant influence of the probe incorporation temperature on the spectral shape. More precisely, the amount of the broad component in a composite ESR spectrum increases with the increasing probe incorporation temperature. A simple model which describes the probe distribution inside the inhomogeneous NR matrix is proposed.

ESR ; natural rubber ; probe-incorporation temperature ; spin probe ; swelling

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