engleski

Local molecular dynamics in rubber nanocomposites

Nanocomposite rubber films were prepared from natural rubber (NR) crosslinked with sulfur. Samples were doped with nanosilica and organically modified clays (Cloisite 10A, Cloisite 15A and Cloisite 20A). An effect of the addition of coupling agent was investigated on NR containing nanosilica particles. Nitroxyl radicals 4-oxo-2, 2, 6, 6-tetrametilpiperidin-1-oxyl (TEMPONE) and 4-hydroxy-2, 2, 6, 6-tetrametil-piperidin-1-oxyl (TEMPOL) were used as spin probes. The main objective of this study was to characterize the dynamic behavior of polyisoprene chain segments in the presence of nanofiller. ESR spectra were recorded in tha wide range of temperatures, from −100 °C to 130 °C. Spectra of TEMPONE and TEMPOL measured in the temperature region around 0 °C consist of broad and narrow components being attributed to the slow and fast rotational motions, respectively. An effect of composition (the type and amount of nanofiller) and the presence of coupling agent on the probe dynamics was observed by changes in the spectral shapes and correlational times of broad and narrow components. Spectra were calculated using NLSL program. ESR results are compared with those obtained by DSC, X-ray scattering, TEM and swelling experiments. [1] S. Valić, in Rubber Nanocomposites: Preparation, Properties and Applications, T. Sabu and R. Stephen Eds, John Wiley & Sons, 2010. p. 391-405. [2] M. Petković Didović, PhD Thesis, University of Zagreb, 2012.

Rubber nanocomposite; local dynamics; EPR

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