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    Characterization and modeling of light activated shape memory polymer.

    机译:光活化形状记忆聚合物的表征和建模。

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    摘要

    Shape memory polymers have recently become the focus of research for their unique ability to switch between two modulus states, allowing them to both recover from large amounts of strain as well as support complex loads. Part of this research involves engineering new formulas specifically designed for applications where traditional thermally activated SMPs are not ideal by tailoring the activation method used to transition the polymer. One such class of polymers is those that utilize optical energy at specific wavelengths to create and cleave crosslinks. It is the development of this new class of light activated shape memory polymers (LASMP) that is the focus of the presented work.;Experimental methods are newly created for this novel class of active materials. Several candidate LASMP formulas are then subjected to this set of experiments characterizing their mechanical and optical properties. Experimentally observed variations among the formulae include virgin state modulus, percent change in modulus with stimulus, and in some instances inelastic response.;To expedite the development of LASMP, a first principles multi-scale model based on the polymer's molecular structure is presented and used to predict the stress response of the candidate formulas. Rotational isomeric state (RIS) theory is used to build a molecular model of a phantom polymer chain. Assessment of the resulting conformation is then made via the Johnson family of statistical distributions and Boltzmann statistical thermodynamics. The ability of the presented model to predict material properties based on the molecular structure of the polymer reduces the time and resources required to test new candidate formulas of LASMP as well as aiding in the ability to tailor the polymer to specific application requirements.;While the first principles model works well to identify promising formulas, it lacks precision. The stress contribution from the constraints on the polymer chain's junctions and neighboring chain entanglements is then added to that of the phantom network allowing Young's modulus to be calculated from the predicted stress response of the polymer. Simple extension, equi-biaxial, and shear strain states are modeled and associated predicted material properties presented. The added precision of this phenomenological extension will aid device design.
    机译:形状记忆聚合物最近因其在两种模量状态之间切换的独特能力而成为研究重点,使它们既能从大量应变中恢复,又能支撑复杂的载荷。这项研究的一部分涉及通过设计用于过渡聚合物的活化方法,为专门设计用于传统热活化SMP不太理想的应用的新配方工程。一类这样的聚合物是那些利用特定波长的光能来产生和裂解交联的聚合物。正是这一类新型的光活化形状记忆聚合物(LASMP)的开发成为了本论文的重点。新的实验方法是针对这类新型的活性材料。然后,将几个候选LASMP公式进行这组实验,以表征其机械和光学特性。实验观察到的公式之间的差异包括原始态模量,模量随刺激变化的百分比以及在某些情况下的非弹性响应。为了加快LASMP的发展,提出并使用了基于聚合物分子结构的第一原理多尺度模型预测候选公式的应力响应。旋转异构状态(RIS)理论用于建立幻影聚合物链的分子模型。然后通过Johnson分布的统计分布和Boltzmann统计热力学对所得构象进行评估。提出的模型基于聚合物的分子结构预测材料性能的能力减少了测试LASMP新候选分子式所需的时间和资源,并有助于根据特定的应用要求定制聚合物。第一原理模型很好地用于确定有前途的公式,但缺乏精度。然后将来自对聚合物链结和相邻链缠结的约束的应力贡献添加到幻象网络的应力贡献中,从而可以从聚合物的预测应力响应中计算出杨氏模量。对简单的延伸状态,等双轴状态和剪切应变状态进行了建模,并给出了相关的预测材料特性。这种现象学扩展的增加的精度将有助于设备设计。

    著录项

    • 作者

      Beblo, Richard Vincent.;

    • 作者单位

      University of Pittsburgh.;

    • 授予单位 University of Pittsburgh.;
    • 学科 Engineering, Mechanical.;Engineering, Materials Science.
    • 学位 Ph.D.
    • 年度 2010
    • 页码 217 p.
    • 总页数 217
    • 原文格式 PDF
    • 正文语种 eng
    • 中图分类 ;
    • 原文服务方 国家工程技术数字图书馆
    • 关键词

      ;

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