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Fracture behavior of nano-scale rubb...

Bacigalupo, Lauren N.,

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Fracture behavior of nano-scale rubber-modified epoxies /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Fracture behavior of nano-scale rubber-modified epoxies // Lauren N Bacigalupo.
Author:	Bacigalupo, Lauren N.,
Description:	1 electronic resource (146 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 75-06, Section: B.
Contained By:	Dissertations Abstracts International75-06B.
Subject:	Polymer chemistry. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3598871
ISBN:	9781303478079

Fracture behavior of nano-scale rubber-modified epoxies /
Bacigalupo, Lauren N.,

Fracture behavior of nano-scale rubber-modified epoxies /Lauren N Bacigalupo. - 1 electronic resource (146 pages)

Source: Dissertations Abstracts International, Volume: 75-06, Section: B.

The primary focus of the first portion of this study is to compare physical and mechanical properties of a model epoxy that has been toughened with one of three different types of rubber-based modifier: a traditional telechelic oligomer (phase separates into micro-size particles), a core-shell latex particle (preformed nano-scale particles) and a triblock copolymer (self-assembles into nano-scale particles). The effect of modifier content on the physical properties of the matrix was determined using several thermal analysis methods, which provided insight into any inherent alterations of the epoxy matrix. Although the primary objective is to study the role of particle size on the fracture toughness, stiffness and strength were also determined since these properties are often reduced in rubber-toughened epoxies. It was found that since the CSR- and SBM-modified epoxies are composed of less rubber, thermal and mechanical properties of the epoxy were better maintained. In order to better understand the fracture behavior and mechanisms of the three types of rubber particles utilized in this study, extensive microscopy analysis was conducted. Scanning transmission electron microscopy (STEM) was used to quantify the volume fraction of particles, transmission optical microscopy (TOM) was used to determine plastic damage zone size, and scanning electron microscopy (SEM) was used to assess void growth in the plastic zone after fracture. By quantifying these characteristics, it was then possible to model the plastic damage zone size as well as the fracture toughness to elucidate the behavior of the rubber-modified epoxies. It was found that localized shear yielding and matrix void growth are the active toughening mechanisms in all rubber-modified epoxies in this study, however, matrix void growth was more prevalent. The second portion of this study investigated the use of three acrylate-based triblocks and four acrylate-based diblocks to modify a model epoxy system. By varying block lengths and the polarity of the epoxy-miscible blocks, a variety of morphologies were generated (such as spherical micelles, layer particles and worm-like micelles). It was found that in some cases, the epoxy-miscible block did not yield domains substantial enough to facilitate increases in toughness. Overall, the thermal and mechanical properties of the acrylate-based triblock- and diblock-modified epoxies were found to be similar to CTBN-modified epoxy, which was used as a control. However, there were properties that were improved with the acrylate-based diblock-modified epoxies when compared to the acrylate-based triblock modified epoxies. Specifically, the viscosity penalty of the diblock-modified epoxies was shown to be a marked improvement over the triblock-modified epoxies, especially given that the fracture toughness values are similar. This reduction in the viscosity penalty becomes an important criterion when considering processing procedures and applications. Additionally, comparing the morphology of the resulting modified-epoxies utilizing atomic force microscopy (AFM) and scanning electron microscopy (SEM) led to a better understanding of the relationship between the particle morphology obtained and the physical properties of the acrylate-based rubber-modified epoxy systems in this research.

English

ISBN: 9781303478079Subjects--Topical Terms:

3173488
Polymer chemistry.
Subjects--Index Terms:

Fracture toughness

Fracture behavior of nano-scale rubber-modified epoxies /
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100 1 $a Bacigalupo, Lauren N., $e author. $3 3765875
245 1 0 $a Fracture behavior of nano-scale rubber-modified epoxies / $c Lauren N Bacigalupo.
264 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2013
300 $a 1 electronic resource (146 pages)
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500 $a Source: Dissertations Abstracts International, Volume: 75-06, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisors: Pearson, Raymond A. Committee members: Barsotti, Robert; Coulter, John P.; Nied, Herman F.; Vinci, Richard P.
502 $b Ph.D. $c Lehigh University $d 2013.
520 $a The primary focus of the first portion of this study is to compare physical and mechanical properties of a model epoxy that has been toughened with one of three different types of rubber-based modifier: a traditional telechelic oligomer (phase separates into micro-size particles), a core-shell latex particle (preformed nano-scale particles) and a triblock copolymer (self-assembles into nano-scale particles). The effect of modifier content on the physical properties of the matrix was determined using several thermal analysis methods, which provided insight into any inherent alterations of the epoxy matrix. Although the primary objective is to study the role of particle size on the fracture toughness, stiffness and strength were also determined since these properties are often reduced in rubber-toughened epoxies. It was found that since the CSR- and SBM-modified epoxies are composed of less rubber, thermal and mechanical properties of the epoxy were better maintained. In order to better understand the fracture behavior and mechanisms of the three types of rubber particles utilized in this study, extensive microscopy analysis was conducted. Scanning transmission electron microscopy (STEM) was used to quantify the volume fraction of particles, transmission optical microscopy (TOM) was used to determine plastic damage zone size, and scanning electron microscopy (SEM) was used to assess void growth in the plastic zone after fracture. By quantifying these characteristics, it was then possible to model the plastic damage zone size as well as the fracture toughness to elucidate the behavior of the rubber-modified epoxies. It was found that localized shear yielding and matrix void growth are the active toughening mechanisms in all rubber-modified epoxies in this study, however, matrix void growth was more prevalent. The second portion of this study investigated the use of three acrylate-based triblocks and four acrylate-based diblocks to modify a model epoxy system. By varying block lengths and the polarity of the epoxy-miscible blocks, a variety of morphologies were generated (such as spherical micelles, layer particles and worm-like micelles). It was found that in some cases, the epoxy-miscible block did not yield domains substantial enough to facilitate increases in toughness. Overall, the thermal and mechanical properties of the acrylate-based triblock- and diblock-modified epoxies were found to be similar to CTBN-modified epoxy, which was used as a control. However, there were properties that were improved with the acrylate-based diblock-modified epoxies when compared to the acrylate-based triblock modified epoxies. Specifically, the viscosity penalty of the diblock-modified epoxies was shown to be a marked improvement over the triblock-modified epoxies, especially given that the fracture toughness values are similar. This reduction in the viscosity penalty becomes an important criterion when considering processing procedures and applications. Additionally, comparing the morphology of the resulting modified-epoxies utilizing atomic force microscopy (AFM) and scanning electron microscopy (SEM) led to a better understanding of the relationship between the particle morphology obtained and the physical properties of the acrylate-based rubber-modified epoxy systems in this research.
546 $a English
590 $a School code: 0105
650 4 $a Polymer chemistry. $3 3173488
650 4 $a Materials science. $3 543314
653 $a Fracture toughness
653 $a Morphology
653 $a Properties
653 $a Rubber modified epoxy
690 $a 0495
690 $a 0794
710 2 $a Lehigh University. $b Polymer Science and Engineering. $e degree granting institution. $3 3765876
720 1 $a Pearson, Raymond A. $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 75-06B.
790 $a 0105
791 $a Ph.D.
792 $a 2013
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3598871