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Publikācija: Effects of Plasticizer and Strain on the Percolation Threshold in Polyisoprene–Carbon Nanocomposites: Positron Annihilation Lifetime Spectroscopy and Electrical Resistance Measurements

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Nosaukums oriģinālvalodā Effects of Plasticizer and Strain on the Percolation Threshold in Polyisoprene–Carbon Nanocomposites: Positron Annihilation Lifetime Spectroscopy and Electrical Resistance Measurements
Pētniecības nozare 2. Inženierzinātnes un tehnoloģijas
Pētniecības apakšnozare 2.5. Materiālzinātne
Autori Māris Knite
Juris Zavickis
Valdis Teteris
A.J. Hill
S.J. Pas
Atslēgas vārdi Polyisoprene– carbon nanocomposite; Percolation transition; Electrical properties; Strain sensor materials; Plasticizer; Positron annihilation lifetime spectroscopy (PALS)
Anotācija A study of the effects of plasticizer and stretching strain on the percolation transition in polyisoprene–carbon nanocomposites (PCNC) is reported. The ortho-positronium (oPs) accessible free volume sites are measured by positron annihilation lifetime spectroscopy (PALS) in relaxed and stretched PCNC samples containing different amounts of plasticizer. The lifetime of oPs, s3, is related to the size of the free volume, and the intensity, I3, to the concentration of free volume sites. The number of free volume cavities is found to decrease during stretching regardless of the content of either carbon nanoparticles (CNP) or plasticizer. The free volume cavity size reaches its maximum value in the region of percolation transition. The percolation threshold is determined by measurements of electrical resistance (ERM). Both PALS and ERM show that the percolation threshold shifts to higher concentration of CNP under stretching strain. A shift of the percolation threshold to lower concentration of CNP was observed for addition of plasticizer. It is interesting that addition of CNP increases the mean size of free volume cavities below the percolation threshold and decreases it at CNP concentrations exceeding the percolation threshold. The relative number of free volume cavities represented by I3 also decreases at CNP concentrations exceeding the percolation threshold. The results are interpreted as filling of cavities above the percolation threshold. ERM during application of cyclic tensile stress revealed fatigue of the tensoresistance effect in samples containing 10 m.p. of CNP with and without added plasticizer.
DOI: 10.1016/j.msec.2005.09.033
Hipersaite: http://www.sciencedirect.com/science/article/pii/S0928493105002717 
Atsauce Knite, M., Zavickis, J., Teteris, V., Hill, A., Pas, S. Effects of Plasticizer and Strain on the Percolation Threshold in Polyisoprene–Carbon Nanocomposites: Positron Annihilation Lifetime Spectroscopy and Electrical Resistance Measurements. Materials Science and Engineering, 2006, Vol.26, Iss.5–7, 771.-775.lpp. ISSN 0928-4931. Pieejams: doi:10.1016/j.msec.2005.09.033
ID 3235