Rheological Study of Polymers Used as Viscosity Index Improvers for Automotive Lubricant Oils

• 作者: Ana Paula Lelis Rodrigues de Oliveira Ana Paula Pena Almeida Cynthia D’ávila Carvalho Erbetta Maria Elisa Scarpelli Ribeiro e Silva Ricardo Geraldo de Sousa Roberto Fernando de Souza Freitas
• 来源期刊: 现代物理(英文)
• 学科: 医学
• 关键词: VISCOSITY INDEX Improvers AUTOMOTIVE Lubricants RHEOLOGY VISCOSITY INDEX Polymer ADDITIVES
• 年，卷（期）: 2014,（12）
• 页码范围: 1085-1093
• 页数: 9页
• 分类号: R73

摘要

In this work, a rheological study of automotive lubricant oils, neutral light paraffinic (NLP) and neutral medium paraffinic (NMP), additivated with two commercial viscosity index improvers-VIIs, based on hydrogenated poly (isoprene-co-styrene), at different concentrations, was carried out. The study included the determination of the kinematic viscosity of the mixtures, the calculation of the viscosity indexes and their behavior when subjected to various rheometric experiments, including stress sweep, steady state flow, creep and recovery, and temperature ramp oscillatory tests. The obtained results showed the efficacy of the additives as viscosity index improvers, enabling a significant increase in the viscosity index of the pure oils at relatively low concentrations. The determination of the storage (G’) and of the loss (G”) moduli for the mixtures oil/VII additives showed a large predominance of the viscous effect over the elastic one. Except when under low shear stress, the mixtures showed a pseudoplastic behavior, with the flow curves being adjusted to fit the Ostwald-de-Waele model (Power Law), with negative flow behavior indexes.