The quantitative evaluation of fracture surface roughness and crack propagation resistance in epoxy resin.

Abstract

In this paper, the fracture surface of epoxy resin is investigated precisely with an interference microscope. In order to explain the characteristics of the fracture surface, the maximum roughness was measured by a technique of pattern analysis on interference fringes. The relation between crack propagation behavior and fracture surface roughness was also discussed. The results obtainedc are briefly summarized as follows; 1) Fracture surface roughness is precisely and quantitatively obtained by analysis of the interference fringe pattern. 2) The maximum roughness of the fracture surface shows dependence on temperature. A characteristic feature of roughness variation is seen just after the onset of crack growth. 3) The value of resistance for crack propagation J'1 measured at 10 μm propagation just after the onset of crack growth, proved to be constant under any temperature condition. Thus, it is implied that the micromechanism of the local fracture at the propagating crack tip is influenced by molecular mobility which reflects time-and temperature-dependent behavior of microheterogeineties of molecular entanglement.