Sorption and diffusion of n-alkanes into bromobutyl rubber membranes w
ere investigated in the temperature interval 25-60 degrees C by a sorp
tion gravimetric method. The Fickian diffusion equation was used to ca
lculate the diffusion coefficients, which were dependent on the size o
f the alkanes, their interactions with the chain segments of the polym
er and temperature. The diffusion coefficients varied from 0.34 x 10(-
7) cm(2)/s (n-hexadecane) to 9.94 x 10(-7) cm(2)/s (n-hexane). The act
ivation energy for diffusion varied from 14 kJ/mol (n-hexane) to 27 kJ
/mol (n-hexadecane). Heat of sorption ranged from -1.4 kJ/mol for n-he
ptane to 2.0 kJ/mol for n-hexadecane. The sorption/swelling results ar
e discussed in terms of first and second order kinetic equations. The
molar mass between chain-entanglement-crosslinks was estimated from sw
elling data. The experimental and calculated results showed a systemat
ic dependence on the increasing size of the alkanes. None of the solve
nts showed any degradative effects on the polymer.