Boonta Hetayothin, Roy Cabaniss, F. Blum
Nov 9, 2012
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Influential Citations
10
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Journal
Macromolecules
Abstract
Deuterium solid-state NMR and temperature-modulated differential scanning calorimetry were used to probe the dynamics of the plasticizer di(propylene glycol) dibenzoate (DPGDB-d10) in mixtures with poly(vinyl acetate) (PVAc). The plasticizer, deuterated in the phenyl rings, was synthesized, and 2H NMR spectra were obtained from PVAc samples with 10, 22, 27, and 37% deuterated plasticizer content as a function of temperature. The dynamics of the plasticizer in the plasticized polymer system were found to be heterogeneous with respect to different plasticizer molecules undergoing different motions. The experimental 2H NMR line shapes were fitted using a set of simulated spectra obtained from the MXQET program. The simulations were based on the superposition of two types of motion: a two-site jump motion, i.e., 180° ring flips, plus isotropic motions. The presence of the polymer allowed more plasticizer molecules to undergo 180° ring flips than in the bulk plasticizer. For the average of the log of the rate ...