Regulation Of The SMI Structures And Its Application As Pour Point Depressant For Crude Oil

Poly(styrene-co-maleimide) (SMI) is an important copolymer which has excellent applications, and has received intensive attentions in recent years. Poly (styrene-co-N-octadecyl maleimide) (SNODMI) is compatible and eutectic with paraffin in the crude oil because of the long alkyl side chains. On the other hand, its main chain is attached to the surface of the paraffin to perturbate the layered structure of the paraffin, resulting in the decreased the pour point of crude oil. In this work, a series of poly (styrene-co-maleicanhydride) (SMA) with different structures were amidated and then imidizated to produce the SNODMI, and the influence of the polymer structure on their performance as the pour point depressant for crude oil was studied.Firstly, the effects of SNODMI with variuos degree of imidization on crystallization temperature, crystalline morphology, complex viscosity and yield stress sand were discussed. It has been found that the increase in the imidization degree of SNODMI can reduce the crystallization temperature (Tc), pour point, the size of wax crystal and the yield stres. When SNODMI1000P with 100% degree of imidization is used, the Tc is decreased by 3.6℃, pour point is reduced by 7℃, and wax crystals is transfered from the original layered structure into a dispersed granular, the yield stress τy is reduced by more than 70 times.To obtain SNODMI of different degree imidization, we explored kinetics of amidification (ring-opening reaction) and imidization (ring-closing reaction) of SMA. Because the amidification of SMA and ODA is very quick, the amidation kinetics of SMA and aniline was further investigated. The results showed that for the amidation of SMA1000P, SMA2000P and SMAEF40 with aniline in THF solution, conversion rate increases with increasing reaction time and temperature. The amidation of SMA with aniline was found to be a second order reaction. Arrhenius equation of the amidation of three kind of SMA with aniline was derived according to the second order reaction mechanism. Kinetics of imidization was also studied. It is a zero order reaction. The reaction rate constants of imidization of ODA with SMA1000P, SMA2000P and SMAEF40 were separately obtained to produce SNODMI with varying degrees of imidization, which was employed as pour point depressant for crude oil above.Secondly, alt-SMA was synthesized by RAFT polymerization and then amidificated and imidizated to prepare alt-SNODMI in order to study the effect of molecular weight and molecular weight distribution (PDI) of their performance as the pour point depressants for model waxy oil. It has been found that alt-SMA synthesized by RAFT polymerization has controlled molecular weight and narrow molecular weight distribution and alt-SNODMI is a good pour point depressant. For C24 as paraffin in decane waxy oil, with increasing Mn, crystallization temperature Tc, complex viscosity η*, the size of wax crystal and yield stress ιy are all decreased. narrow MWD also enhance the performance of pour point depressants.