Naslov
ESR - Spin Probe Method in Studying Nanocomposite Rubber Materials

Autori
Valić, Srećko ; Didović, Mirna ; Klepac, Damir ; Lekić, Andrica ; Meera, A.P. ; Thomas, Sabu

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Proceedings of the International Conference of Hi-Tech Materials : ICHTM-09 / Das, Chapal K. - Kharagpur : IIT Kharagpur ; DMSRDE Kanpur, 2009, 20-20

Skup
International Conference of Hi-Tech Materials

Mjesto i datum
Kharagpur, Indija, 11.02.2009. - 13.02.2009

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
ESR-spin probe; nanocomposite; rubber; segmental dynamics

Sažetak
Natural rubber (NR) samples crosslinked by sulphur were doped by two types of nanofiller: nanosilica particles and organically modified nanoclay (cloisite 20A). The amount of nanofiller was varied from 2 phr to 10 phr. Some of the samples with nanosilica contained different portions of the coupling agent. The basic characterization of samples was made by TEM, XRD and DSC. Electron spin resonance (ESR) spectroscopy, known to be a powerful tool in studying segmental dynamics, was applied to investigate the dynamic and structural changes of NR matrix influenced by the presence of nanofiller. The free nitroxide radical 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (spin probe) was incorporated into NR matrix by swelling the samples in toluene probe solution. Spectra were measured in a wide temperature range from -100 °C to 130 °C. The ESR results show a strong influence of the nanofiller on motional behavior of the chain segments. A notable correlation between the nanosilica amount and the broad component of ESR spectra, characteristic for the slow segmental motions, has been obtained. The presence of the coupling agent and its effect on the motional inhomogeneity of NR matrix has been observed too. ESR spectra of the spin probe incorporated in nanocomposites of natural rubber (NR) with various loadings of organically modified clay (cloisite 20A) indicate a combination of the intercalation and exfoliation of clay lamellae in the polymer matrix, with dominating intercalation at higher filler loadings. Spectra of the composite material highly differ from those of the pristine NR, especially in the higher temperature region ; the shape of the spectra also depends on the filler content. These results indicate that nanoclay has a strong influence on the segmental motions of polymer chains. The origin of the hindered motion of chain segments observed for temperatures higher than 100 º C is still under consideration.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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