title: NMR relaxation dispersion of vulcanized natural rubber.
abstract: The dependence of the 1H spin-lattice relaxation time on the magnetic field strength has been determined for linear and cross-linked polyisoprene for Larmor frequencies between 5 kHz and 20 MHz. Universal power-law relations are found for all temperatures and cross-link densities under investigation and are compared to published results of rotating-frame experiments on similar natural rubber samples. The shape of the individual dispersion functions can be superposed into a master curve using appropriate shift factors. While addition of filler particles even at large weight fractions has only a minor effect on the relaxation times, uniaxial deformation and swelling are demonstrated to alter the molecular dynamics significantly.
authors.affiliation: Lehrstuhl für Makromolekulare Chemie and Magnetic Resonance Center MARC, ITMC, RWTH Aachen, Worringerweg 1, D-52074 Aachen, Germany.
authors.forename: Sobiroh
authors.initials: S
authors.lastname: Kariyo
authors.forename: Siegfried
authors.initials: S
authors.lastname: Stapf
mesh_terms: D002070:Butadienes / Q000737:chemistry*; D004548:Elasticity; D045782:Hemiterpenes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D008968:Molecular Conformation; D009038:Motion; D010420:Pentanes / Q000737:chemistry*; D012408:Rubber / Q000032:analysis / Q000737:chemistry* / Q000145:classification; D013314:Stress, Mechanical; D013696:Temperature
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene; D012408:Rubber