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Nanotube-Matrix Interplay and Tunability in Ultrahigh Volume-Fraction Aligned Carbon Nanotube Poly(Urethane-urea) Nanocomposites.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Nanotube-Matrix Interplay and Tunability in Ultrahigh Volume-Fraction Aligned Carbon Nanotube Poly(Urethane-urea) Nanocomposites./
Author:	Gair, Jeffrey L., Jr.
Description:	1 online resource (287 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 79-02(E), Section: B.
Contained By:	Dissertation Abstracts International79-02B(E).
Subject:	Mechanical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9780355292213

Nanotube-Matrix Interplay and Tunability in Ultrahigh Volume-Fraction Aligned Carbon Nanotube Poly(Urethane-urea) Nanocomposites.
Gair, Jeffrey L., Jr.

Nanotube-Matrix Interplay and Tunability in Ultrahigh Volume-Fraction Aligned Carbon Nanotube Poly(Urethane-urea) Nanocomposites. - 1 online resource (287 pages)

Source: Dissertation Abstracts International, Volume: 79-02(E), Section: B.

Thesis (Ph.D.)

Includes bibliographical references

The present dissertation seeks to better understand the nature of biphasic poly(urethane-urea) (PUU) interactions in materials with densely packed, aligned carbon nanotubes (CNTs). Of particular interest are the CNT-matrix interactions with in-situ polymerized PUU of various stoichiometric ratios. A novel synthesis method for PUU which permits fabrication of PUU-based polymer nanocomposites (PNCs) has been developed. Study of the thermal and multiscale mechanical behavior of stoichiometrically varied PUU materials has been conducted to demonstrate significant interaction between the matrix and CNTs, both in terms of morphology and mechanical reinforcement.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780355292213Subjects--Topical Terms:

557493
Mechanical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Nanotube-Matrix Interplay and Tunability in Ultrahigh Volume-Fraction Aligned Carbon Nanotube Poly(Urethane-urea) Nanocomposites.
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245 1 0 $a Nanotube-Matrix Interplay and Tunability in Ultrahigh Volume-Fraction Aligned Carbon Nanotube Poly(Urethane-urea) Nanocomposites.
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300 $a 1 online resource (287 pages)
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500 $a Source: Dissertation Abstracts International, Volume: 79-02(E), Section: B.
500 $a Adviser: Hugh A. Bruck.
502 $a Thesis (Ph.D.) $c University of Maryland, College Park $d 2017.
504 $a Includes bibliographical references
520 $a The present dissertation seeks to better understand the nature of biphasic poly(urethane-urea) (PUU) interactions in materials with densely packed, aligned carbon nanotubes (CNTs). Of particular interest are the CNT-matrix interactions with in-situ polymerized PUU of various stoichiometric ratios. A novel synthesis method for PUU which permits fabrication of PUU-based polymer nanocomposites (PNCs) has been developed. Study of the thermal and multiscale mechanical behavior of stoichiometrically varied PUU materials has been conducted to demonstrate significant interaction between the matrix and CNTs, both in terms of morphology and mechanical reinforcement.
520 $a PNCs with CNT Vf up to 30% have been achieved with excellent wetting confirmed via Micro-CT. TGA and DSC have revealed that CNTs stabilize thermal degradation of PUU by inducing crystallinity and reducing phase-mixing. AFM confirmed this by visualizing the crystals present in the matrix materials. CNT-induced crystallinity and phase-separation are attributed to the binding of CNTs to hard segments, which limit chain mobility during polymerization. Higher CNT Vf PNCs were found to increase soft-segment crystallinity, though with diminishing returns. Extreme crystallinity was found at 10% V f CNTs which is though to arise due to an optimized spacing to permit ordered crystal formation of the PUU.
520 $a Enhancements to indentation modulus of up to 1600% in the transverse orientation and 3500% in the axial orientation have been recorded via quasi-static nanoindentation. Greater CNT Vf and greater hard-segment composition lead to reduced chain mobility, and in some instances, can reduce CNT effectiveness in mechanical enhancement. The 10% CNT Vf exhibits greater indentation and storage moduli arising which is thought to arise from an optimized balance of inter-CNT spacing and chain mobility. Furthermore, PUU with higher hard-segment content is highly anisotropic and highly rate-sensitive, indicating significant morphological interactions with inter-CNT spacing of ~18nm. Degradation and increased loss modulus are seen in similar PUU with 20% loading, pointing to weak chain interactions and reduced hydrogen, likely do to confinement and reduced mobility. A model has also been developed which sheds light on the evolution of CNT-matrix interactions across a wide range of CNT volume-fractions.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Mechanical engineering. $3 557493
650 4 $a Materials science. $3 557839
650 4 $a Nanotechnology. $3 557660
655 7 $a Electronic books. $2 local $3 554714
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690 $a 0794
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710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a University of Maryland, College Park. $b Mechanical Engineering. $3 1178917
773 0 $t Dissertation Abstracts International $g 79-02B(E).
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10286635 $z click for full text (PQDT)