Rheologica Acta, Vol.40, No.2, 193-195, 2001
Thermoreversible gels in oil/EVA systems
In this work we investigate the gel formation of EVA/recycled motor oil systems as a route to obtain synthetic binders which could be used instead of natural bitumen, as well as mixed with natural bitumen to modify adequately its viscoelastic response. The EVA. copolymer studied in this work has a vinyl acetate content of 18 wt% and solutions of EVA/motor oil have been prepared up to a concentration of 50 wt%. Dynamic viscoelastic frequency sweeps between 10(-2) Hz and 10(2) Hz have shown that above 3 wt%, at 25 degreesC, EVA/motor oil systems form gels. It has been possible to define an elastic equilibrium modulus, G(e), for each gel. The dependence of G(e) on concentration has been compared with that of PVC/DOP and SBS/oil gels on the basis of the De Gennes model. Thermal stability of EVA/motor oil gels has also been analyzed, indicating that for the highest polymer concentrations gel point is above 80 degreesC.