E‐glass/DGEBA/m‐PDA single fiber composites: Interface debonding during fiber fracture

Abstract

In this paper, we examine the regions of debonding between the fibers and the matrix surrounding fiber breaks formed during single fiber fragmentation tests. The fiber breaks are accompanied by areas of debonding between the matrix and the surface of the fiber. With increasing applied strain, the lengths of these debonded regions generally increase. At the end of the test, the matrix tensile strain adjacent to the debond regions is an order of magnitude higher than the applied strain (40% vs. 4%). Although the debond edges typically remain attached at the same locations on the fiber fragments, debond propagation along fiber fragments under increasing strain has been observed in some cases. The phenomenon is termed secondary debond growth, and two mechanisms that trigger secondary debond region growth have been proposed. As expected, tests with bare fibers and with fibers coated to alter interface adhesion indicate that the average size of debonded regions at the end of the test increases as the calculated interfacial shear strength decreases. However, a decrease in the "apparent" interfacial shear strength resulting from an increase in testing rate results in a decrease in the size of the average debond region. This result suggests an increase in the amount of energy stored in the matrix from the fiber fracture process. POLYM. COMPOS., 28:561-574, 2007.

Influence of Interfacial Properties on Crack Propagation in Fiber‐Reinforced Polymer Matrix Composites

“…According to interfacial fracture mechanics, the crack will reroute around the interface and display a complicated fracture process. [1][2][3][4] For the purpose of predicting damage evolution exactly, investigation of the interfacial strength effects is one crucial issue. The fracture behavior of fibrous composites is characterized by a combination of complex micro-damage events, such as fiber breakage, interface debonding, matrix cracking and fiber being pulling out, due to different interfacial strengths.…”

The single fiber composite test: A comparison of E‐glass fiber fragmentation data with statistical theories

“…The AS-4 carbon fibers were obtained from the Hexcel Corporation. 15 The mold preparation procedure and curing procedure for the E-Glass SFCs made using the diglycidyl ether of bisphenol-A (DGEBA) resin (Epon 828, Shell) cured with meta-phenylenediamine (m-PDA, Fluka, or Sigma-Aldrich) have been published previously by Holmes et al 9,15,16,18,19 McDonough et al 20 have described the procedure for preparing the polyisocyanurate SFCs, and Kim et al 21 have described the procedure for preparing the combinatorial microcomposite SFC specimens used in this report. The AS-4 carbon fiber SFC specimens were prepared by Rich et al using the procedure described in Ref.…”

“…* The fibers were either used as received (bare E-glass fibers) or treated with the n-octadecyl triethoxysilane (NOTS) 16 or glycidyloxypropyl trimethoxysilane (GOPS), with the GOPS surface treatment performed by the procedure given in Ref. 17.…”

A methodology for detecting interfacial debonding in clay/epoxy nanocomposites

“…[12] and references therein), the image change with increasing strain has been interpreted in terms of clay-matrix interface debonding. Since Cloisite 10A, like most of the current clay surface treatment technology, contains a hydrophobic alkyl ammonium salt, covalent bonding between the treated clay and the host matrix is formally precluded.…”