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Characterization and Modeling of Light Activated Shape Memory Polymer

Beblo, Richard Vincent (2010) Characterization and Modeling of Light Activated Shape Memory Polymer. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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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.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Beblo, Richard
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairWeiland, Lisa Maucklmw36@pitt.eduLMW36
Committee MemberLeonard, John
Committee MemberTong, Tat
Committee MemberSlaughter, William S.wss@engr.pitt.eduWSS
Committee MemberClark, William W.wclark@engr.pitt.eduWCLARK
Date: 25 June 2010
Date Type: Completion
Defense Date: 11 December 2009
Approval Date: 25 June 2010
Submission Date: 27 January 2010
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Light Activated SMP; Multiscale Modeling; Shape Memory Polymers
Other ID:, etd-01272010-143003
Date Deposited: 10 Nov 2011 19:31
Last Modified: 15 Nov 2016 13:36


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