Volumetric properties and viscosity of mixtures of a synthetic poly(α-olefin) base oil with polymethacrylate-based polymeric additives have been studied. Two different polymeric additives were evaluated at addition levels up to 7 wt %. Density data were collected at 298, 323, 348, 373, and 398 K from 10 to 40 MPa in a variable-volume view cell. Viscosity data were collected at 298, 323, 348, and 373 K from 10 to 40 MPa in a high-pressure rotational viscometer. The density and viscosity data were then modeled simultaneously by coupling the Sanchez–Lacombe equation state with the free volume and the density scaling theories of viscosity. Density data were also used to evaluate the derived thermodynamic properties such as isothermal compressibility, isobaric thermal expansion coefficient, and internal pressure. The variations in the volumetric properties and viscosity are discussed in terms of the nature of the polymeric additive and polymer concentration in the mixture. It is shown that for each oil, density scaling reduces the viscosity values generated at different temperatures and pressures into a master curve. Density scaling parameters provide new insights into the effectiveness of the polymeric additives as viscosity modifiers in terms of addition levels and the temperature sensitivity of viscosity.

中文翻译：

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高压（高密度）粘度和聚（α-烯烃）基础油与聚合物添加剂的混合物建模

已经研究了合成的聚（α-烯烃）基础油与基于聚甲基丙烯酸酯的聚合物添加剂的混合物的体积特性和粘度。评估了两种不同的聚合物添加剂，其添加量最高为7 wt％。在可变体积的视单元中，从10到40 MPa在298、323、348、373和398 K下收集密度数据。在高压旋转粘度计中从10到40 MPa在298、323、348和373 K下收集粘度数据。然后通过将Sanchez-Lacombe方程状态与自由体积和粘度的密度标定理论耦合在一起，同时对密度和粘度数据进行建模。密度数据还用于评估导出的热力学性质，如等温压缩性，等压热膨胀系数和内部压力。根据聚合物添加剂的性质和混合物中聚合物的浓度讨论了体积特性和粘度的变化。结果表明，对于每种油，密度定标会将在不同温度和压力下产生的粘度值降低到主曲线中。密度缩放参数从添加量和粘度的温度敏感性方面提供了新的见解，以了解聚合物添加剂作为粘度调节剂的有效性。