Temperature dependent fracture behavior in model epoxy networks with nanoscale heterogeneity

Matthew D. Eaton; L. Catherine Brinson; Kenneth R. Shull

doi:10.1016/j.polymer.2021.123560

Temperature dependent fracture behavior in model epoxy networks with nanoscale heterogeneity

Matthew D. Eaton, L. Catherine Brinson, Kenneth R. Shull^*

^*Corresponding author for this work

Materials Science and Engineering

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

20 Scopus citations

Abstract

The role of nanoscale heterogeneity on the mode I fracture toughness, K_Ic, of model epoxy networks has been investigated. Model systems utilized consist of diglycidyl ether of bisphenol A (DGEBA) as the epoxide with a stoichiometric amine mixture of a rigid cycloaliphatic diamine (PACM) and a more flexible, polypropylene glycol based diamine (Jeffamine) at different molar ratios. The molecular weight of the Jeffamine was adjusted to further tailor the epoxy properties. Fracture toughness was measured using single edge notched bend samples and hardness was measured by Vickers indentation. Both measurements were performed at temperatures as low as −100 ̊C to above ambient temperatures. Results are interpreted in the context of the Dugdale model of material toughness where the fracture toughness is expressed in terms of a cohesive zone stress (related to the hardness), the elastic modulus (measured directly) and the crack tip opening displacement (obtained from images of the fracture surfaces). High toughness is obtained in heterogeneous networks where a decrease in the cohesive zone stress is offset by sufficiently large increases in the crack tip opening displacement.

Original language	English (US)
Article number	123560
Journal	Polymer
Volume	221
DOIs	https://doi.org/10.1016/j.polymer.2021.123560
State	Published - Apr 14 2021

Funding

This work was performed under the following financial assistance award 70NANB19H005 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD). This work made use of the MatCI Facility which receives support from the MRSEC Program ( NSF DMR-1720139 ) of the Materials Research Center at Northwestern University. We also acknowledge helpful discussion with J. Lenhart at the Army Research Laboratory. M.D. Eaton acknowledges the support of the Department of Defense (DoD) through the National Defense Science and Engineering Graduate (NDSEG) program as well as through the Richter Trust Funds.

Keywords

Epoxies
Fracture toughness
Network topology

ASJC Scopus subject areas

Organic Chemistry
Polymers and Plastics
Materials Chemistry

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title = "Temperature dependent fracture behavior in model epoxy networks with nanoscale heterogeneity",

abstract = "The role of nanoscale heterogeneity on the mode I fracture toughness, KIc, of model epoxy networks has been investigated. Model systems utilized consist of diglycidyl ether of bisphenol A (DGEBA) as the epoxide with a stoichiometric amine mixture of a rigid cycloaliphatic diamine (PACM) and a more flexible, polypropylene glycol based diamine (Jeffamine) at different molar ratios. The molecular weight of the Jeffamine was adjusted to further tailor the epoxy properties. Fracture toughness was measured using single edge notched bend samples and hardness was measured by Vickers indentation. Both measurements were performed at temperatures as low as −100 ̊C to above ambient temperatures. Results are interpreted in the context of the Dugdale model of material toughness where the fracture toughness is expressed in terms of a cohesive zone stress (related to the hardness), the elastic modulus (measured directly) and the crack tip opening displacement (obtained from images of the fracture surfaces). High toughness is obtained in heterogeneous networks where a decrease in the cohesive zone stress is offset by sufficiently large increases in the crack tip opening displacement.",

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author = "Eaton, {Matthew D.} and Brinson, {L. Catherine} and Shull, {Kenneth R.}",

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doi = "10.1016/j.polymer.2021.123560",

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AU - Brinson, L. Catherine

AU - Shull, Kenneth R.

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Y1 - 2021/4/14

N2 - The role of nanoscale heterogeneity on the mode I fracture toughness, KIc, of model epoxy networks has been investigated. Model systems utilized consist of diglycidyl ether of bisphenol A (DGEBA) as the epoxide with a stoichiometric amine mixture of a rigid cycloaliphatic diamine (PACM) and a more flexible, polypropylene glycol based diamine (Jeffamine) at different molar ratios. The molecular weight of the Jeffamine was adjusted to further tailor the epoxy properties. Fracture toughness was measured using single edge notched bend samples and hardness was measured by Vickers indentation. Both measurements were performed at temperatures as low as −100 ̊C to above ambient temperatures. Results are interpreted in the context of the Dugdale model of material toughness where the fracture toughness is expressed in terms of a cohesive zone stress (related to the hardness), the elastic modulus (measured directly) and the crack tip opening displacement (obtained from images of the fracture surfaces). High toughness is obtained in heterogeneous networks where a decrease in the cohesive zone stress is offset by sufficiently large increases in the crack tip opening displacement.

AB - The role of nanoscale heterogeneity on the mode I fracture toughness, KIc, of model epoxy networks has been investigated. Model systems utilized consist of diglycidyl ether of bisphenol A (DGEBA) as the epoxide with a stoichiometric amine mixture of a rigid cycloaliphatic diamine (PACM) and a more flexible, polypropylene glycol based diamine (Jeffamine) at different molar ratios. The molecular weight of the Jeffamine was adjusted to further tailor the epoxy properties. Fracture toughness was measured using single edge notched bend samples and hardness was measured by Vickers indentation. Both measurements were performed at temperatures as low as −100 ̊C to above ambient temperatures. Results are interpreted in the context of the Dugdale model of material toughness where the fracture toughness is expressed in terms of a cohesive zone stress (related to the hardness), the elastic modulus (measured directly) and the crack tip opening displacement (obtained from images of the fracture surfaces). High toughness is obtained in heterogeneous networks where a decrease in the cohesive zone stress is offset by sufficiently large increases in the crack tip opening displacement.

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KW - Fracture toughness

KW - Network topology

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Temperature dependent fracture behavior in model epoxy networks with nanoscale heterogeneity

Abstract

Funding

Keywords

ASJC Scopus subject areas

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