Influence of Monomer Ratio on the Performance of Poly(octadecyl acrylate-co-styrene) as Pour-Point Depressants

Abstract

The effect of polar monomer styrene content on the effectiveness of the performance of poly­(octadecyl acrylate) (POA) pour-point depressant (PPD) was studied using the model waxy oils (MWOs) and Shengli crude oil. A set of controlled styrene content was copolymerized with octadecyl acrylate to make poly­(octadecyl acrylate-styrene) (POA-S). The performances of POA and POA-S in MWOs and Shengli crude oil were evaluated by measuring their ability to decrease pour points of model waxy oils and waxy crude oil. It was found that when poly­(octadecyl acrylate) and styrene monomer mole ratio was 3:2 the PPD gives optimum performance in MWOs and Shengli crude oil. After POA-S was added to MWO1, MWO2, and Shengli crude oil, the pour points could be reduced by as much as 32, 31, and 19 °C, respectively. The result illustrated that the presence of POA-S in the MWOs, crude oil, and paraffin wax affects the crystallization process, leading to the wax appearance temperature (WAT) decrease in each test. Differential scanning calorimetry (DSC) test showed that the wax crystal phase transformation can occur after POA-S has been doped in MWOs and paraffin wax; the exothermic peak is also split into a doublet. The crystallization performance of paraffin wax was investigated by X-ray diffraction (XRD). The increase in the distance between visible platelet-like wax crystals is observed by scanning electron microscopy (SEM). This result gave reasonable proof in improving the flowability of the MWOs by POA-S.

Chemical Additives as Flow Improvers for Waxy Crude Oil and Model Oil: A Critical Review Analyzing Structure–Efficacy Relationships

“…Four characteristics of side chains/pendants that influence the efficacy of additives were identified, namely, functional group (Zhao et al and Wu et al), pendant length (Li et al and Deshmukh and Bharambhe , ), monomer ratio (Jiang et al, Fu et al., Yang et al), and graft density (Jiang et al). While analyzing the effects of functionality of side chains, Zhao et al studied the effect of replacing the alkyl side chain linked to the amide group in a maleic anhydride-based copolymer, with a benzene ring and a benzimidazole ring (as shown in Figure ).…”

“…Some authors have modified the monomer ratio and have observed the efficacies of the different polymeric additives. − Jiang et al modified the alkyl amide content (octadecyl chain, nonpolar; amide, polar) in maleic anhydride-based polymers. They synthesized polymers with different amidation ratios ( f ), which indicates the number of alkyl amides resulting from maleic anhydride groups.…”

“…They attributed this to the larger graft density of polymers with a large value of ( f ), which was favorable for cocrystallization with wax molecules. Similarly, Fu et al have investigated the effect of monomer mass ratio in octadecyl acrylate and styrene-based polymers. The amounts of octadecyl acrylate and styrene were varied in 2:5, 2:4, 2:3, and 2:2 ratios to produce poly­(octadecyl acrylate–styrene) products having different styrene content .…”

“…Similarly, Fu et al have investigated the effect of monomer mass ratio in octadecyl acrylate and styrene-based polymers. The amounts of octadecyl acrylate and styrene were varied in 2:5, 2:4, 2:3, and 2:2 ratios to produce poly­(octadecyl acrylate–styrene) products having different styrene content . Their synthesis procedure is illustrated in Scheme .…”

“…The amounts of octadecyl acrylate and styrene were varied in 2:5, 2:4, 2:3, and 2:2 ratios to produce poly(octadecyl acrylate−styrene) products having different styrene content. 75 Their synthesis procedure is illustrated in Scheme 1. The PPD with a 2:3 ratio gave optimum effects on the rheological properties of waxy crude oil and model oil.…”