A Direct Comparison of the Fragmentation Test and the Microbond Pull-out Test for Determining the Interfacial Shear Strength

Abstract

Experiments were conducted to compare the fragmentation test with the microbond pull-out test for determining the interfacial shear strength between carbon AS4 fibers and a thermoset matrix consisting of a Di-Glycidyl Ether of Bisphenol A (DGEBA) resin cured with a diamine (metaphenylenediamine, m-PDA) curing agent. The results indicate that, for the microbond test, diffusion of the rather volatile m-PDA curing agent at early stages of cure leads to low values of interfacial shear strengths when compared with results obtained for the same system with the fragmentation test.With the microbond test, a distinct relationship between the glass transition temperature of the droplets and their size is noticed. Smaller (<150ym) droplets have very low Tg's and are incompletely cured. While changing to a modified curing cycle and/or using a m-PDA-rich curing environment alleviates the diffusion problem, the interfacial shear strength values are still not in good agreement with the fragmentation test results. Microbond data from another system consisting of DGEBA resin cured with a different, less volatile dimaine curing agent indicates that diffusion of the curing agent becomes less severe as the volatility of the curing agent decreases and the corresponding microbond interfacial shear strengths agree better with fragmentation test results.KEY WORDS Single fiber fragmentation test; microbond pullout test; interfacial shear strength; interface; fiber-matrix adhesion; variable stoichiometry effect on epoxy properties.

Effects of thermal residual stress on interfacial properties of polyphenylene sulphide/carbon fibre (PPS/CF) composite by microbond test

“…1). Other researchers [28][29][30][31][32][33] have also reported similar results. This phenomenon indicates that some as-yet-unexplained experimental factors have not been corrected in the evaluation of IFSS.…”

Thermo-hydrolytic resistance of polyepoxide–glass fibres interfaces by the microbond test

“…In fact, polymeric microdroplets can exhibit properties different from that of the bulk matrix. The specific geometry of the specimens can lead to a loss of stoechiometry, especially in the case of polyepoxide matrices [27,28]. Losses in glass transition temperature were reported for polyepoxide microdroplets based on a diglycidyl ether of bisphenol A (DGEBA) epoxyde prepolymer combined to aliphatic and aromatic amines co-monomer as well as anhydrides.…”

Effects of electrophoretically deposited carbon nanofibers on the interface of single carbon fibers embedded in epoxy matrix

“…Additionally, several researchers have used the fiber fragmentation test to investigate the effect of sizing, resin hardener, and environmental conditions on interface stress transfer [34][35][36][37][38][39]. Further review of these testing methods has been performed by Herrera-Franco and Drzal [1], Rao et al [27], Hamada et al [40] and Zhandarov and Mäder [12].…”

“…The mechanical properties of the droplet may also be impacted by the volatility of the curing agent within the resin-hardener system. Rao et al [27] proposed that the interfacial properties of the matrix may be impacted by variations in curing agent density.…”