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首頁(yè)> 外文學(xué)位 >Contact mechanics studies of polymer gels with the quartz crystal microbalance.
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Contact mechanics studies of polymer gels with the quartz crystal microbalance.

機(jī)譯：聚合物凝膠與石英晶體微量天平的接觸力學(xué)研究。

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摘要

This thesis examines the surfaces of polymer gels using a novel technique that combines the contact mechanics approach of Johnson, Kendall, and Roberts (JKR) with the quartz crystal microbalance (QCM). Polymer gels are well-suited for a variety of applications, but their surface compositions often depend on their environmental surroundings due to the activity of the gel solvent. The JKR technique is sensitive to bulk mechanical properties and surface adhesive forces, while the QCM is sensitive to surface mechanical properties. In this thesis, the combined JKR-QCM technique is used to study the surfaces of polymer gels.; In a typical JKR-QCM experiment, a hemispherical gel is brought into and out of contact with the QCM surface at a controlled velocity, and the resulting load, displacement, contact area, and complex resonant frequency of the QCM are measured. It is shown that the changes in complex resonant frequency of the QCM in such an experiment are related to the material's surface mechanical properties, which include its high frequency viscosity.; Existing QCM theory is not intended to account for a changing interfacial contact area, which is a common feature in JKR experiments. Equations are presented to account for variable coverage of the QCM by considering the radial sensitivity profile across the quartz crystal. QCM theory is also modified for experiments involving a growing contact area between a viscoelastic material and the crystal surface when submerged in a liquid.; JKR-QCM studies of a model polymer gel, composed of a physically crosslinked triblock copolymer swollen by mineral oil, reveal a concentrated oil layer at the gel's surface that is transferred to the quartz crystal after loading and subsequent detachment of the gel. The same features are noted for the model gel submerged in water. A different model gel, composed of a chemically crosslinked polymer swollen by water, reveals evidence of a surface water layer when brought into contact with a QCM surface that is submerged in mineral oil.
機(jī)譯：本文使用一種結(jié)合了Johnson，Kendall和Roberts（JKR）的接觸力學(xué)方法與石英晶體微量天平（QCM）的新穎技術(shù)來(lái)檢查聚合物凝膠的表面。聚合物凝膠非常適合各種應(yīng)用，但由于凝膠溶劑的活性，其表面組成通常取決于其周圍環(huán)境。 JKR技術(shù)對(duì)整體機(jī)械性能和表面粘合力敏感，而QCM對(duì)表面機(jī)械性能敏感。本文結(jié)合JKR-QCM技術(shù)研究了聚合物凝膠的表面。在典型的JKR-QCM實(shí)驗(yàn)中，使半球形凝膠以受控的速度與QCM表面接觸和脫離接觸，并測(cè)量由此產(chǎn)生的載荷，位移，接觸面積和QCM的復(fù)共振頻率。結(jié)果表明，在這種實(shí)驗(yàn)中，QCM的復(fù)共振頻率的變化與材料的表面力學(xué)性能有關(guān)，包括高頻粘度?，F(xiàn)有的QCM理論無(wú)意解決界面接觸面積的變化，這是JKR實(shí)驗(yàn)的共同特征。通過(guò)考慮整個(gè)石英晶體的徑向靈敏度曲線，提出了方程來(lái)說(shuō)明QCM的可變覆蓋范圍。 QCM理論也被修改，用于涉及浸入液體中時(shí)粘彈性材料與晶體表面之間接觸面積不斷增大的實(shí)驗(yàn)。 JKR-QCM對(duì)模型聚合物凝膠的研究表明，該凝膠由礦物油溶脹的物理交聯(lián)的三嵌段共聚物組成，在凝膠表面發(fā)現(xiàn)了濃縮的油層，該油層在加載和隨后分離后轉(zhuǎn)移到石英晶體中。對(duì)于浸沒(méi)在水中的模型凝膠，注意到相同的特征。由水溶脹的化學(xué)交聯(lián)聚合物組成的另一種模型凝膠，當(dāng)與浸在礦物油中的QCM表面接觸時(shí)，揭示出表面水層的跡象。

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  • 作者

    Nunalee, Frank Nelson.;

  • 作者單位

    Northwestern University.;

  • 授予單位 Northwestern University.;
  • 學(xué)科 Engineering Materials Science.
  • 學(xué)位 Ph.D.
  • 年度 2005
  • 頁(yè)碼 204 p.
  • 總頁(yè)數(shù) 204
  • 原文格式 PDF
  • 正文語(yǔ)種 eng
  • 中圖分類 工程材料學(xué);
  • 關(guān)鍵詞

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