title: How we can interpret the T1 dispersion of MC, HPMC and HPC polymers above glass temperature?
abstract: The chain dynamics in methyl cellulose (MC), hydroxypropylmethyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) were studied with the aid of field-cycling NMR relaxometry technique in the temperature range from 300 to 480 K that is above the glass transition, but below thermal degradation. The frequency dependence of proton spin-lattice relaxation time was determined between 24 kHz and 40 MHz for selected temperatures. The experimental spin-lattice relaxation dispersion data were fitted with the power law relations of T(1) proportional variant omega(gamma) predicted by the tube/reptation model. The exponent's values found from the fitting procedure for MC, HPMC and HPC almost exactly match the ones predicted in tube/reptation model for limit II (gamma=0.75) and in MC also for limit III (gamma=0.50). Remarkably, this finding concerns the polymers in networks formed of the same polymer species.
authors.affiliation: Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland. radam@ifmpan.poznan.pl
authors.forename: Adam
authors.initials: A
authors.lastname: Rachocki
authors.forename: Joanna
authors.initials: J
authors.lastname: Kowalczuk
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Tritt-Goc
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D065347:Hypromellose Derivatives; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry*; D013696:Temperature
chemical_list: D065347:Hypromellose Derivatives; D002482:Cellulose; D008747:Methylcellulose; C008079:hydroxypropylcellulose