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Deformation and failure mechanism of...

Lee, Jong-Young.

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Deformation and failure mechanism of nanostructured polymer thin films.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Deformation and failure mechanism of nanostructured polymer thin films./
Author:	Lee, Jong-Young.
Description:	164 p.
Notes:	Adviser: Alfred Crosby.
Contained By:	Dissertation Abstracts International68-11B.
Subject:	Chemistry, Polymer. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3289267
ISBN:	9780549330806

Deformation and failure mechanism of nanostructured polymer thin films.
Lee, Jong-Young.

Deformation and failure mechanism of nanostructured polymer thin films. - 164 p.

Adviser: Alfred Crosby.

Thesis (Ph.D.)--University of Massachusetts Amherst, 2007.

In this research, we develop models to describe the impact of nanostructures on the elastic deformation and failure of polymer thin films. First, we use polystyrene-b-poly(2-vinyl-pyridine) as a model material to investigate the effect of nanodomains and surface terracing on the crazing process. Here, we find that well-aligned lamellar domains can alter the extension ratio of craze fibrils and delay craze growth rate. Additionally, nanoscaled surface terraces impede the craze initiation and significantly decrease the failure strain of polymer thin films.

ISBN: 9780549330806Subjects--Topical Terms:

1018428
Chemistry, Polymer.

Deformation and failure mechanism of nanostructured polymer thin films.
LDR:03153nam 2200325 a 45 001 957406
005 20110630
008 110630s2007 ||||||||||||||||| ||eng d
020 $a 9780549330806
035 $a (UMI)AAI3289267
035 $a AAI3289267
040 $a UMI $c UMI
100 1 $a Lee, Jong-Young. $3 1280758
245 1 0 $a Deformation and failure mechanism of nanostructured polymer thin films.
300 $a 164 p.
500 $a Adviser: Alfred Crosby.
500 $a Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7370.
502 $a Thesis (Ph.D.)--University of Massachusetts Amherst, 2007.
520 $a In this research, we develop models to describe the impact of nanostructures on the elastic deformation and failure of polymer thin films. First, we use polystyrene-b-poly(2-vinyl-pyridine) as a model material to investigate the effect of nanodomains and surface terracing on the crazing process. Here, we find that well-aligned lamellar domains can alter the extension ratio of craze fibrils and delay craze growth rate. Additionally, nanoscaled surface terraces impede the craze initiation and significantly decrease the failure strain of polymer thin films.
520 $a To investigate the impact of inorganic nanodomains on the crazing process, we use a model and well-dispersed nanocomposite of polystyrene blended with surface modified cadmium selenide nanoparticles (diameter &sim;3.5 nm). With this material design, enthalpic interaction is minimized and entropic interaction dominates the mechanical properties. Due to high surface-to-volume ratio of nanoparticles and nanoparticle-polymer entropic interaction, the elastic modulus of our nanocomposites decreases as a function of volume fraction of nanoparticles (V). During craze formation and growth, nanoparticles undergo three stages of rearrangement: (1) alignment along the precraze, (2) expulsion from craze fibrils, and (3) assembly into clusters entrapped among craze fibrils. This entropically-driven rearrangement leads to the altered craze morphology and an increase in failure strain by 60% at an optimal V. This optimal volume fraction is related to the balance of two mechanisms: (1) the decrease in the volume fraction of cross-tie fibrils, and (2) the decrease in extensibility of the craze.
520 $a In the last part of this research project, larger nanoparticles (diameter is &sim;6.0 nm) are used to increase nanoparticle-polymer entropic interaction. Here, we find that nanoparticles segregate to the film surface during the film casting process on the substrate. This entropically-driven segregated layer of nanoparticles leads to a significant drop in the elastic modulus at very low V (0.2%) and an increase in failure strain by 100% in an optimal V.
590 $a School code: 0118.
650 4 $a Chemistry, Polymer. $3 1018428
690 $a 0495
710 2 $a University of Massachusetts Amherst. $b Polymer Science & Engineering. $3 1018485
773 0 $t Dissertation Abstracts International $g 68-11B.
790 $a 0118
790 1 0 $a Crosby, Alfred, $e advisor
790 1 0 $a Dinsmore, Anthony $e committee member
790 1 0 $a Emrick, Todd $e committee member
790 1 0 $a Gido, Samuel $e committee member
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3289267