J. Phys. IV France 03 (1993) C4-249-C4-252
Water absorption in novolac epoxy resins studied by positron annihilationT. MIURA1, T. SUZUKI1, Y. OKI1, M. NUMAJIRI1, K. KONDO1, Y. SHIOMI2 and Y. ITO3
1 National Laboratory for High Energy Physics, Radiation Control Center, Oho, Tsukuba, Ibaraki 305, Japan
2 Tsukuba Research Laboratory, Sumitomo Chemical Co. LTD, Kitahara, Tsukuba, Ibaraki 300-32, Japan
3 Research Center for Nuclear Science and Technology, The University of Tokyo, Tokai, Ibaraki 319-11, Japan
Water absorption rates of four kinds of epoxy resins cured with phenol novolac (PH) were compared with the results of positron annihilation lifetime measurements (PAL). Three samples : cresol novolac (CR), tetra-methyl-biphenol (TMB) and bis-phenol A (BA), showed almost similar absorption rates, while tris-hydroxy-phenyl-methane (THPM) absorbed water twice as fast as others. Since THPM has a larger τ3 value (hence larger intermolecular-space holes) than the other samples, the correlation between τ3 and the absorption rate seems evident. For THPM, the lifetime distribution was shifted toward a shorter lifetime after absorbing water, which is interpreted in terms of the particular structure of three-dimensional holes.
© EDP Sciences 1993