How we can interpret the T1 dispersion of MC, HPMC and HPC polymers above glass temperature?
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.
Rachocki
Adam
A
Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland. radam@ifmpan.poznan.pl
Kowalczuk
Joanna
J
Tritt-Goc
Jadwiga
J
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
D065347:Hypromellose Derivatives; D002482:Cellulose; D008747:Methylcellulose; C008079:hydroxypropylcellulose