engleski

Chain dynamics in natural rubber nanocomposites

Natural rubber (NR) crosslinked with various amount of sulfur was doped by two types of nanofiller: silica (without and with coupling agent) and organically modified clays (Cloisite 10A, Cloisite 15A and Cloisite 20A). Samples were investigated by electron spin resonance (ESR) spectroscopy, known also as electron paramagnetic resonance (EPR) spectroscopy. 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. Spin probe method was applied to characterize the dynamic behavior of polyisoprene chain segments in the presence of nanofiller. ESR spectra were recorded in a 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. The effect of the type and amount of nanofiller, as well as the influence of coupling agent on the probe motions are accompanied by the changes in the amount of broad and narrow component and correlational times. Spectra were calculated using NLSL program. ESR results are correlated with those obtained by other methods: DSC, X-ray scattering, TEM, 2H-NMR and swelling. [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.

Natural rubber; nanocomposite; chain dynamics; ESR - spin probe

nije evidentirano