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首页> 外文学位 >Understanding Siloxane-Based Lubricants and Developing a Polymer Chemistry-Based Rheological-Tribological Model.
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Understanding Siloxane-Based Lubricants and Developing a Polymer Chemistry-Based Rheological-Tribological Model.

机译：了解基于硅氧烷的润滑剂并开发基于聚合物化学的流变摩擦模型。

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摘要

Silicon-oxygen or 'siloxane' based polymers are known for low viscosity-temperature dependence, low glass transition temperature and high oxidative stability due in part to strong and flexible molecular bonds. The unique properties of siloxanes have led to evaluation of their performance as lubricants. Through collaboration with Prof. Marks' Chemistry group on synthesis and Prof. Chung's Materials Science and Engineering group on surface science, we designed, synthesized and tested a number of polysiloxanes and compared their performances to several commercially available polysiloxanes, polyalphaolefin, and polyether lubricants.;Molecular masses and chemical structures were determined by gel permeation chromatography and nuclear magnetic resonance, respectively. Density and viscosity were measured over a temperature range of 298 to 398K. Elastohydrodynamic film thickness, friction, and wear measurements were made at loads and speeds that represent the boundary, mixed and full film lubrication regimes. The investigations reveal that lubricant film formation and friction performance vary significantly with different length, branch content, and atomic constituents.;The experimental results were used in conjunction with theories of rheology and lubrication to develop a molecular-rheological modeling system that uses polysiloxane alkyl branch length L, pendant type J, percent of branch functional monomers Q, and degree of polymerization DP to predict viscosity, pressure-viscosity index, shear modulus, and limiting shear stress over a range of temperatures and pressures. The rheological properties are used to project film formation, boundary friction, and film friction over a range of slide-to-roll ratios and entrainment speeds. A mathematical bridge is thereby built to relate molecular structure to tribological performance, considering non-Newtonian characteristics.;An optimization algorithm has been developed to predict desired lubricant structures with a set of rheological and tribological characteristics. The boundary friction due to asperity interaction and film friction due to viscous dissipation were used as constraints to develop both Newtonian traction and non-Newtonian energy-efficient lubricants fluids with improved wear protection. The insights into the structural-functional characteristics of siloxanes facilitate the design of advanced lubricants to maximize film formation yet vary hydrodynamic friction for a range of engineering applications.
机译：众所周知，基于硅氧或“硅氧烷”的聚合物具有较低的粘度温度依赖性，较低的玻璃化转变温度和较高的氧化稳定性，这部分归因于牢固而灵活的分子键。硅氧烷的独特性能已导致对其作为润滑剂的性能进行评估。通过与Marks教授的化学合成小组和Chung的材料科学与工程小组表面科学小组合作，我们设计，合成和测试了许多聚硅氧烷，并将它们的性能与几种市售的聚硅氧烷，聚α烯烃和聚醚润滑剂进行了比较。 ；分子质量和化学结构分别通过凝胶渗透色谱法和核磁共振法测定。在298至398K的温度范围内测量密度和粘度。在代表边界，混合和全膜润滑方式的载荷和速度下进行了弹性流体动力学膜的厚度，摩擦和磨损测量。研究表明，润滑剂膜的形成和摩擦性能随长度，支链含量和原子组成的不同而发生显着变化。；将实验结果与流变学和润滑理论结合起来，开发了一种使用聚硅氧烷烷基支链的分子流变建模系统长度L，侧链类型J，支链官能团单体Q的百分比和聚合度DP，以预测在一定温度和压力范围内的粘度，压力-粘度指数，剪切模量和极限剪切应力。流变性质用于在一定的滑动比和夹带速度范围内预测薄膜形成，边界摩擦和薄膜摩擦。因此，考虑到非牛顿特性，建立了将分子结构与摩擦学性能相关联的数学桥梁。;已经开发了一种优化算法，以预测具有一组流变学和摩擦学特性的所需润滑剂结构。由于粗糙相互作用引起的边界摩擦和由于粘性耗散引起的薄膜摩擦被用作开发牛顿牵引力和非牛顿高效节能润滑油的约束条件，从而改善了耐磨性。对硅氧烷的结构功能特性的深入了解有助于设计先进的润滑剂，以最大程度地形成膜，同时改变一系列工程应用中的流体动力摩擦。

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  • 作者

    Zolper, Thomas.;

  • 作者单位

    Northwestern University.;

  • 授予单位 Northwestern University.;
  • 学科 Engineering Mechanical.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 218 p.
  • 总页数 218
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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