| Abstract
| - High-density polyethylene (HDPE) and polypropylene (PP) were studied to identify tailor-made materialsfor walls of pipelines and ducts for crude paraffinic oil that inhibit paraffin depositions. The interfacialinteraction was investigated from 50 to 70 °C and as a function of the n-C36H74 paraffin concentration addedto the paraffinic crude oil. The static and the dynamic interfacial tensions were observed, respectively, bytraditional contact angle measurements and by fluorescence depolarization of the natural fluorescent probesof the crude oil, flowing at a high rate. The static interaction showed a low dependence on the n-paraffincontent for both surfaces. For PP, it decreased slightly as the n-paraffin concentration increased, evidencingan increase in the liquid−liquid interaction. The dynamic interfacial tension with PP clearly decreased astemperature and n-paraffin concentration increased, the latter effect being attributed to the PP methyl groupshindering the interaction between the n-paraffin and the PP main chain. For the flow on HDPE, the interactionproved to be highly dependent on the n-paraffin concentration and temperature. It increased as n-paraffinwas added and temperature decreased. The former effect is attributed to the alignment of the n-paraffin chainswithin the high rate flowing liquid and the similar molecular geometry of the n-paraffin and the linear polymersurface (almost without branches), which increases the number of sites available for interaction. PP provedto be more suitable for transportation of crude oil rich in paraffins with more than 36 carbon atoms, whileHDPE was more suitable for those with smaller paraffinic chains.
|
