In order to explore the influences of the alkyl chain length and type of polar groups of the PPDs (pour point depressants) on the crystallization characteristics and flow ability of crude oil, a series of new maleic anhydride derivative graft modified EVA (ethylene vinyl acetate) copolymers PPDs were synthesized. All the new copolymers were characterized by fourier transforms infrared (FT-IR) spectrum analysis, proton nuclear magnetic resonance (¹H NMR) and gel permeation chromatography (GPC). The results showed that all the new PPDs exhibited better performance in improving the fluidity and delaying the gelling of crude oil than EVA PPD. Moreover, copolymer containing alkyl chain with 18 carbon atoms exhibited better performance than those bearing alkyl chains of other carbon number in depressing the pour point, a pour point drop up to 19 ℃ was obtained by using 0.1 wt% of that PPD, which was conductive to co-crystallization of PPD molecules and wax molecules. However, copolymer containing benzene ring exhibited the best performance in depressing the pour point by 22 ℃ at the concentration of 0.1 wt%, which can change the growth characteristics of wax crystals and delay the aggregation of asphaltene and resin, thus effectively improve the flow ability of crude oil.

为了探讨PPDs（降凝剂）的烷基链长和极性基团类型​​对原油结晶特性和流动性的影响，一系列新型马来酸酐衍生物接枝改性EVA（乙烯醋酸乙烯酯）合成了共聚物 PPD。所有新共聚物均通过傅里叶变换红外 (FT-IR) 光谱分析、质子核磁共振 ( ¹H NMR）和凝胶渗透色谱（GPC）。结果表明，与EVA PPD相比，所有新型PPD在改善原油流动性和延缓原油胶凝方面均表现出更好的性能。此外，含有18个碳原子的烷基链的共聚物在降低倾点方面表现出比带有其他碳原子数的烷基链的共聚物更好的性能，使用0.1 wt%的PPD获得了高达19 ℃的倾点下降，该PPD具有导电性。 PPD分子和蜡分子的共结晶。而含苯环的共聚物在0.1 wt%的浓度下将倾点降低22 ℃的性能最好，可以改变蜡晶体的生长特性，延缓沥青质和树脂的聚集，从而有效提高流动性的原油。