Microdeformation behavior in nanotemplated epoxy thermosets: A study with in situ tensile deformation technique in transmission electron microscopy

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 47; no. 4; pp. 393 - 406
• Main Authors: Tang, Houxiang Sean, Hermel-Davidock, Theresa J, Hahn, Stephen F, Murray, Dan J, Cieslinski, Robert C, Verghese, Nikhil E, Pham, Ha Q
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.02.2009; Wiley
• Subjects: Applied sciences; block copolymers; epoxy resin; Exact sciences and technology; in situ deformation test; Mechanical properties; microdeformation; nanoheterogeneity; nanotoughening; Organic polymers; Physicochemistry of polymers; poly(ethyleneoxide); Properties and characterization; TEM; Microdeformation; Strengthening; block copolymers; Bromine containing polymer; Epoxy resin; Isoprene derivative copolymer; Ethylene oxide copolymer; Experimental study; Mechanism; nanoheterogeneity; poly(ethyleneoxide); Saturated copolymer; in situ deformation test; nanotoughening; TEM; Block copolymer; Elongation (mechanics); Modified material
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.21644

Microdeformation behavior in nanostructured block copolymer-toughened epoxy resins, or templated epoxy thermosets, was studied using an in situ tensile deformation technique performed directly in a transmission electron microscope. The observed microdeformation modes were found to correlate well with the macroscopic mechanical properties of the materials. In the order of decreasing macroscopic fracture toughness, the microdeformation modes were observed to change from large uniform plastic deformation over an extensive area, to localized plastic deformation bands, to little plastic deformation observed in the most brittle material. A similar trend was also observed when samples of the same material were tested at different temperatures, reflecting changes in the deformation mechanism as a function of temperature. Structural defects were observed in nanotoughening phases when plastic deformation was observed. The implication of the observed microdeformation modes to the macroscopic toughening mechanisms is discussed in the context of the micromorphology of the nanometer sized toughening phases and parameters of the epoxy matrix chemistry such as bromination, molecular weight, and interfacial miscibility.