A polarized micro-Raman study of necked epoxy fibers. (16th September 2021)

• Record Type: Journal Article
• Authors: Sui, XiaoMeng; Pinkas, Iddo; Wagner, H. Daniel
• Is Part Of: Polymer. Volume 230(2021)
• Publication Date: 2021-09-16
• Subjects: Epoxy fiber -- Polarized micro-Raman -- Molecular reorientation; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2021.124034
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Fully cured epoxy resins are typically brittle materials but according to recent research, cured epoxy fibers exhibit a singular mechanical behavior, including yielding followed by large deformation, and very high strength, toughness, and modulus. These properties appear to intensify as the fiber diameter decreases. The microstructural origin of this unusual behavior has not been fully determined. Here we use confocal polarized Raman spectroscopy to monitor the apparent molecular reorientation induced by plastic deformation of epoxy fibers, both qualitatively and quantitatively. Based on these and previous X-ray diffraction measurements, a likely molecular explanation for the extreme mechanical behavior of micro-sized epoxy fibers is proposed. Graphical abstract: Image 1 Highlights: Micro-sized epoxy fibers show extensive necking under tensile stress. Polarized micro-Raman reveals molecular orientation in the necked regions. Molecular orientation is not observed outside the necked region of the fibers.