Synergistic effects of radiation and stress on mechanical properties organic composite materials

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Mechanical tests (creep and relaxation tests by bending) are made during irradiation in order to examine synergistic effects of radiation and stress on mechanical properties.The 1994th period : 1.Samples are engineering plastics ie.epoxy resin and glass fiber reinforced epoxy resin. 2.Radiation sources are gamma-ray of Co-60 and electron beam of linac at ISIR.3.An alminum vessel for irradiation test was made, which was able to be filled with liquid nitrogen, in order to avoid thermal destruction of polymers by irradiation. 4.The material's degradation is found to be accelerated by snergestic effects of radiation and stress.The 1995th period. 5.Examining chmical processes in polymers of synergistic effects of radiation and stress, the dependency of the creep rates during irradiation on the enviromental temperature was investigated. The appearent activate energy for the rate in the synergistic test is smaller than that of the irrdiatet only material. The difference of degradation mechansm is, therefore, assumed btween the synergistic condition and the only irradiated condition.The 1996th period : 6.Radicals from ESR measurement in the synergistic test specimen are 10 % larger than those in the irrdiated one. 7.Scissions of molecular chain are found to be 10 % increased by synergistic effect according to vibrational tests and swelling tests. 8.The mechanism of acceleration in degradation of organic materials is proposed as followings ; 1) From macroscopic view point, decrease of the viscosity in Maxwell model. 2) Scissions increase and the effect of crosslinkage disappear in the synergistic condition.