Adhesion Strength of Block Copolymer Toughened Epoxy on Aluminum

Vincent Pang; Zachary J. Thompson; Guy D. Joly; Frank S. Bates; Lorraine F. Francis

doi:10.1021/acsapm.9b00909

Adhesion Strength of Block Copolymer Toughened Epoxy on Aluminum

Vincent Pang, Zachary J. Thompson, Guy D. Joly, Frank S. Bates, Lorraine F. Francis

Research output: Contribution to journal › Article › peer-review

30 Scopus citations

Abstract

The effect of poly(ethylene-alt-propylene)-b-poly(ethylene oxide) block copolymer modifiers on the adhesion strength of epoxies was evaluated. Three block copolymer modifiers of varying block weight fractions were synthesized and mixed into the epoxy precursors and cured, forming well-dispersed nanoscale structures in the epoxy matrix. The symmetric block copolymers formed spherical micelles, and the asymmetric block copolymer with shorter poly(ethylene oxide) blocks formed small bilayer vesicles in the epoxy matrix. For both block copolymer nanostructure morphologies, compact tension tests of bulk specimens showed that modified epoxies exhibited a significant improvement in critical strain energy release rate, GIc, over the neat epoxy with no reduction in the elastic modulus. When spherical micelle modified epoxies were used as adhesives for aluminum, single-lap-joint shear tests showed an apparent adhesion strength enhancement of up to ∼46%, with increased cohesive failure. Electron micrographs of the topological features on the fracture surfaces of these materials indicate that micelle cavitation plays a role in both the toughening and adhesion strength enhancement of these epoxies. By contrast, a 28% reduction in adhesion strength was observed in the bilayer vesicle modified epoxies. Possible mechanisms for the disparate adhesion strength results for the two types of block copolymer modified epoxies are discussed.

Original language	English (US)
Pages (from-to)	464-474
Number of pages	11
Journal	ACS Applied Polymer Materials
Volume	2
Issue number	2
DOIs	https://doi.org/10.1021/acsapm.9b00909
State	Published - Feb 14 2020

Bibliographical note

Funding Information:
This work was funded and supported by the 3M Company. V.P. acknowledges support from the 3M Science and Technology Fellowship. The authors extend their gratitude to Harrison Wenzel for assistance in specimen preparation and data collection. Parts of this work were performed in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program.

Publisher Copyright:
Copyright © 2019 American Chemical Society.

Keywords

adhesion strength
block copolymers
compact tension
epoxy
single-lap-joint
toughening

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@article{bda2e384cc6a47859df07f09764c2d61,

title = "Adhesion Strength of Block Copolymer Toughened Epoxy on Aluminum",

abstract = "The effect of poly(ethylene-alt-propylene)-b-poly(ethylene oxide) block copolymer modifiers on the adhesion strength of epoxies was evaluated. Three block copolymer modifiers of varying block weight fractions were synthesized and mixed into the epoxy precursors and cured, forming well-dispersed nanoscale structures in the epoxy matrix. The symmetric block copolymers formed spherical micelles, and the asymmetric block copolymer with shorter poly(ethylene oxide) blocks formed small bilayer vesicles in the epoxy matrix. For both block copolymer nanostructure morphologies, compact tension tests of bulk specimens showed that modified epoxies exhibited a significant improvement in critical strain energy release rate, GIc, over the neat epoxy with no reduction in the elastic modulus. When spherical micelle modified epoxies were used as adhesives for aluminum, single-lap-joint shear tests showed an apparent adhesion strength enhancement of up to ∼46%, with increased cohesive failure. Electron micrographs of the topological features on the fracture surfaces of these materials indicate that micelle cavitation plays a role in both the toughening and adhesion strength enhancement of these epoxies. By contrast, a 28% reduction in adhesion strength was observed in the bilayer vesicle modified epoxies. Possible mechanisms for the disparate adhesion strength results for the two types of block copolymer modified epoxies are discussed. ",

keywords = "adhesion strength, block copolymers, compact tension, epoxy, single-lap-joint, toughening",

author = "Vincent Pang and Thompson, {Zachary J.} and Joly, {Guy D.} and Bates, {Frank S.} and Francis, {Lorraine F.}",

note = "Funding Information: This work was funded and supported by the 3M Company. V.P. acknowledges support from the 3M Science and Technology Fellowship. The authors extend their gratitude to Harrison Wenzel for assistance in specimen preparation and data collection. Parts of this work were performed in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Publisher Copyright: Copyright {\textcopyright} 2019 American Chemical Society.",

year = "2020",

month = feb,

day = "14",

doi = "10.1021/acsapm.9b00909",

language = "English (US)",

volume = "2",

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AU - Pang, Vincent

AU - Thompson, Zachary J.

AU - Joly, Guy D.

AU - Bates, Frank S.

AU - Francis, Lorraine F.

N1 - Funding Information: This work was funded and supported by the 3M Company. V.P. acknowledges support from the 3M Science and Technology Fellowship. The authors extend their gratitude to Harrison Wenzel for assistance in specimen preparation and data collection. Parts of this work were performed in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Publisher Copyright: Copyright © 2019 American Chemical Society.

PY - 2020/2/14

Y1 - 2020/2/14

N2 - The effect of poly(ethylene-alt-propylene)-b-poly(ethylene oxide) block copolymer modifiers on the adhesion strength of epoxies was evaluated. Three block copolymer modifiers of varying block weight fractions were synthesized and mixed into the epoxy precursors and cured, forming well-dispersed nanoscale structures in the epoxy matrix. The symmetric block copolymers formed spherical micelles, and the asymmetric block copolymer with shorter poly(ethylene oxide) blocks formed small bilayer vesicles in the epoxy matrix. For both block copolymer nanostructure morphologies, compact tension tests of bulk specimens showed that modified epoxies exhibited a significant improvement in critical strain energy release rate, GIc, over the neat epoxy with no reduction in the elastic modulus. When spherical micelle modified epoxies were used as adhesives for aluminum, single-lap-joint shear tests showed an apparent adhesion strength enhancement of up to ∼46%, with increased cohesive failure. Electron micrographs of the topological features on the fracture surfaces of these materials indicate that micelle cavitation plays a role in both the toughening and adhesion strength enhancement of these epoxies. By contrast, a 28% reduction in adhesion strength was observed in the bilayer vesicle modified epoxies. Possible mechanisms for the disparate adhesion strength results for the two types of block copolymer modified epoxies are discussed.

AB - The effect of poly(ethylene-alt-propylene)-b-poly(ethylene oxide) block copolymer modifiers on the adhesion strength of epoxies was evaluated. Three block copolymer modifiers of varying block weight fractions were synthesized and mixed into the epoxy precursors and cured, forming well-dispersed nanoscale structures in the epoxy matrix. The symmetric block copolymers formed spherical micelles, and the asymmetric block copolymer with shorter poly(ethylene oxide) blocks formed small bilayer vesicles in the epoxy matrix. For both block copolymer nanostructure morphologies, compact tension tests of bulk specimens showed that modified epoxies exhibited a significant improvement in critical strain energy release rate, GIc, over the neat epoxy with no reduction in the elastic modulus. When spherical micelle modified epoxies were used as adhesives for aluminum, single-lap-joint shear tests showed an apparent adhesion strength enhancement of up to ∼46%, with increased cohesive failure. Electron micrographs of the topological features on the fracture surfaces of these materials indicate that micelle cavitation plays a role in both the toughening and adhesion strength enhancement of these epoxies. By contrast, a 28% reduction in adhesion strength was observed in the bilayer vesicle modified epoxies. Possible mechanisms for the disparate adhesion strength results for the two types of block copolymer modified epoxies are discussed.

KW - adhesion strength

KW - block copolymers

KW - compact tension

KW - epoxy

KW - single-lap-joint

KW - toughening

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Adhesion Strength of Block Copolymer Toughened Epoxy on Aluminum

Abstract

Bibliographical note

Keywords

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MRSEC IRG-2: Sustainable Nanocrystal Materials

MRSEC IRG-3: Hierarchical Multifunctional Macromolecular Materials

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Adhesion Strength of Block Copolymer Toughened Epoxy on Aluminum

Abstract

Bibliographical note

Keywords

MRSEC Support

Publisher link

Find It

Other files and links

Fingerprint

Projects

MRSEC IRG-2: Sustainable Nanocrystal Materials

MRSEC IRG-3: Hierarchical Multifunctional Macromolecular Materials

MRSEC Program DMR-1420013

Cite this