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Title: Characterizing the Viscoelastic Behavior of PDMS/PDPS Copolymers.

Abstract

Abstract not provided.

Authors:
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1367485
Report Number(s):
SAND2017-6087T
654102
DOE Contract Number:
AC04-94AL85000
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English

Citation Formats

Small, Mark E. Characterizing the Viscoelastic Behavior of PDMS/PDPS Copolymers.. United States: N. p., 2017. Web.
Small, Mark E. Characterizing the Viscoelastic Behavior of PDMS/PDPS Copolymers.. United States.
Small, Mark E. Thu . "Characterizing the Viscoelastic Behavior of PDMS/PDPS Copolymers.". United States. doi:.
@article{osti_1367485,
title = {Characterizing the Viscoelastic Behavior of PDMS/PDPS Copolymers.},
author = {Small, Mark E.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}

Thesis/Dissertation:
Other availability
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  • Abstract not provided.
  • The factors influencing the viscoelastic behavior of short-fiber and particulate composites were examined from both a theoretical and experimental viewpoint. The Aggregate Model, based on the elastic bounding results of Wu and McCullough, was reviewed. The model combines the properties of the pure components with the volume fraction, orientation, and aspect ratio distributions of the fiber phase to predict mechanical properties. This model was converted to creep and dynamic mechanical models assuming quasi-static viscoelasticity. The elastic and viscoelastic behavior of neat, cross-linked polyester was characterized. It was shown that thermoreversible physical aging significantly affected the creep response of the neatmore » polyester. Smooth master cures for extended time were generated by the use of a single temperature shift function. Prediction of creep response from short-term dynamic mechanical analysis is in good agreement with observed creep response when aging shift factors were introduced. Static and creep characteristics of several glass-filled polyesters were obtained.« less
  • The central theme of this thesis work is to develop new block copolymer materials for biomedical applications. While there are many reports of stimuli-responsive amphiphilic [19-21] and crosslinked hydrogel materials [22], the development of an in situ gel forming, pH responsive pentablock copolymer is a novel contribution to the field, Figure 1.1 is a sketch of an ABCBA pentablock copolymer. The A blocks are cationic tertiary amine methacrylates blocked to a central Pluronic F127 triblock copolymer. In addition to the prerequisite synthetic and macromolecular characterization of these new materials, the self-assembled supramolecular structures formed by the pentablock were experimentally evaluated.more » This synthesis and characterization process serves to elucidate the important structure property relationships of these novel materials, The pH and temperature responsive behavior of the pentablock copolymer were explored especially with consideration towards injectable drug delivery applications. Future synthesis work will focus on enhancing and tuning the cell specific targeting of DNA/pentablock copolymer polyplexes. The specific goals of this research are: (1) Develop a synthetic route for gel forming pentablock block copolymers with pH and temperature sensitive properties. Synthesis of these novel copolymers is accomplished with ATRP, yielding low polydispersity and control of the block copolymer architecture. Well defined macromolecular characteristics are required to tailor the phase behavior of these materials. (2) Characterize relationship between the size and shape of pentablock copolymer micelles and gel structure and the pH and temperature of the copolymer solutions with SAXS, SANS and CryoTEM. (3) Evaluate the temperature and pH induced phase separation and macroscopic self-assembly phenomenon of the pentablock copolymer. (4) Utilize the knowledge gained from first three goals to design and formulate drug delivery formulations based on the multi-responsive properties of the pentablock copolymer. Demonstrate potential biomedical applications of these materials with in vitro drug release studies from pentablock copolymer hydrogels. The intent of this work is to contribute to the knowledge necessary for further tailoring of these, and other functional block copolymer materials for biomedical applications.« less
  • The influence of microstructural features on the elastic and viscoelastic properties of Polyetheretherketone (PEEK) and short carbon fiber reinforced PEEK was investigated. A composites approach was employed to first model the properties of the semicrystalline polymer as a composite material and later to model the properties of the short-fiber composite. The Aggregate Model was used in conjunction with experimental moduli for the amorphous and semicrystalline polymer to extract an estimate for the crystalline modulus. The crystalline modulus was subsequently used to predict the creep response at intermediate levels of crystallinity. Creep and dynamic mechanical responses at elevated temperatures were interrelatedmore » by the use of temperature-time-frequency superposition principle to obtain the long-term prediction for the creep response. The viscoelastic response was found to be affected by the physical aging phenomenon. The effect of aging on elastic and viscoelastic properties was observed at all attainable levels of crystallinity. Calorimetric studies have been conducted to assess the influences of aging on the enthalpy relaxation of amorphous and semicrystalline PEEK. Short carbon-fiber-reinforced PEEK was characterized for the elastic and viscoelastic response.« less