"Self-concentration" effects on the dynamics of a polychlorinated biphenyl diluted in 1,4-polybutadiene

Abstract

The mobility of isolated polychlorinated biphenyl (PCB54) in 1,4-polybutadiene (PB) has been investigated by means of broadband dielectric spectroscopy. The aim was to provide new insights about the effect of the environment on the dynamics of PCB54. The authors' results indicate that PCB54 structural dynamics is neither independent of the PB matrix nor slaved to the matrix itself. The authors interpret these results as a consequence of the limited size of cooperatively rearranging regions (CRRs) involved in PCB54 structural relaxation possessing an effective concentration different from the macroscopic one. This implies a non-negligible influence of "self-concentration," already proven for the component segmental dynamics in polymer blends, also in the relaxation of binary mixtures involving low molecular weight glass formers. This allowed the evaluation of the size of CRR, which was about 1nm for PCB54 in PB. This means that the cooperativity extends over the first shell around PCB54 molecules. ; The authors acknowledge the University of the Basque Country and Basque Country Government -9/UPV00206.215-13568/2001 and Spanish Minister of Education MAT 2004-01617 for their support. The support of the European Community with the SoftComp program -Project No. NMP3-CT-2004-502235 is also acknowledged. ; Peer reviewed