Abstract Herein, four asphaltenes in distinguished polarities were first fractionated from heavy crude oil by the solvent-precipitation method (that is, C5I asphaltenes) and characterized, and the effects of asphaltenes on the polyethylene-vinyl acetate (EVA) PPD's performance for the model waxy oil were evaluated. Results show that the asphaltenes in lower polarities contain a greater number of aliphatic groups and present a higher H/C ratio, hence exhibiting better oily compatibility and the greater synergistic performance with EVA in improving the waxy oil flowability at low temperatures. The competition between the co-crystallization and nucleation effect of additives determines the wax precipitating temperature (WPT). Adding asphaltenes delays the wax precipitation, but increases wax crystal number just below WPT, especially together with EVA. According to the micro-observation and isothermal titration tests, EVA can adsorb onto the asphaltene aggregates to form the composite EVA/asphaltene particles, and the adsorption gradually reaches saturated with the EVA injecting. The composite particles act as the heterogeneous crystallizing templates for wax molecules to precipitate, triggering the formation of wax crystal flocs with large size, spherical-like morphology, and compact structure. Reducing the asphaltenes polarity strengthens the stronger interactions among asphaltenes, EVA and paraffin wax molecules, and hence improves the EVA/asphaltene synergistic performance.

中文翻译：

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极性沥青质有助于提高聚乙烯-醋酸乙烯酯的流动性能

摘要 本文首先采用溶剂沉淀法从重质原油中分馏出四种不同极性的沥青质（即 C5I 沥青质）并对其进行表征，并针对该模型研究了沥青质对聚乙烯-醋酸乙烯（EVA）PPD 性能的影响。评价蜡油。结果表明，较低极性的沥青质含有更多的脂肪族基团，呈现出更高的H/C比，因此在改善蜡质油低温流动性方面表现出更好的油相容性和与EVA更大的协同性能。添加剂的共结晶和成核作用之间的竞争决定了蜡沉淀温度 (WPT)。添加沥青质会延迟蜡沉淀，但会增加刚好低于 WPT 的蜡晶体数，尤其是和EVA一起。根据显微观察和等温滴定试验，EVA可以吸附在沥青质骨料上形成复合EVA/沥青质颗粒，并且随着EVA的注入，吸附逐渐达到饱和。复合颗粒作为蜡分子沉淀的异质结晶模板，引发了具有大尺寸、球形形态和致密结构的蜡晶体絮凝体的形成。降低沥青质极性增强了沥青质、EVA和石蜡分子之间更强的相互作用，从而提高了EVA/沥青质的协同性能。随着EVA的注入，吸附逐渐达到饱和。复合颗粒作为蜡分子沉淀的异质结晶模板，引发了具有大尺寸、球形形态和致密结构的蜡晶体絮凝体的形成。降低沥青质极性增强了沥青质、EVA和石蜡分子之间更强的相互作用，从而提高了EVA/沥青质的协同性能。随着EVA的注入，吸附逐渐达到饱和。复合颗粒作为蜡分子沉淀的异质结晶模板，引发了具有大尺寸、球形形态和致密结构的蜡晶体絮凝体的形成。降低沥青质极性增强了沥青质、EVA和石蜡分子之间更强的相互作用，从而提高了EVA/沥青质的协同性能。