Encontro realizado em Alacalá de Henares (Madrid), de 22 a 25 de Setembro de 2014Dialkyl adipates are a class of esters materials used as components of lubricants and plasticizers.
Diffusion of plasticizers in polymers is a complex process that is difficult to study [1].
As a contribution to understand this phenomenon, the self-diffusion coefficients of five dialkyl adipates (dimethyl, diethyl, dipropyl, dibuthyl and bis(2-ethylhexyl)) were measured by the PFGSTE method in the temperature range 20 to 60ºC. It was shown that these compounds follow the Stokes-Einstein equation [2]. In effect, the self-diffusion coefficients change linearly with T.η-1(η is the viscosity). The dependence of the activation energies for self-diffusion is discussed in terms of size and branching of the alkyl chains of the adipates.
Molecular dynamics (MD) simulations were done for these sytems in order to predict the diffusion
coefficients as a function of temperature [3].
Acknolwedgements:
This work was supported by the Strategic Projects PEst-OE/QUI/UI0100/2011 and PEst-OE/QUI/
UI0100/2013, both funded by Fundação para a Ciência e a Tecnologia (FCT, Portugal). We thank also FCT
for funding the NMR facility through Project RECI/QEQ-QIN/0189/2012.
References:
[1] Rahman M.; Brazel C. S., Prog. Polym. Sci. 2004, 29, 1223–1248.
[2] Price W.S, NMR Studies of Translation Motion, Cambridge University Press, Cambridge, 2009.
[3] Pereira, L. A. M.; Martins, L. F. G.; Ascenso, J. R; Morgado, P.; Ramalho, J. P. P.; Filipe, E. J. M., J. Chem. Eng. Data 2014, accepted for publication
