Cu powders dispersed ABS polymers were prepared by solution cast, which could easily control the dispersion ratio. The Cu addition gradually enhanced the electrical conductivity at less and more less than the critical volume fraction (19.0±1.0 volCu) in ABS polymer. The jump of electrical conductivity was observed by the Cu addition at the critical volume fraction. The result was explained by the percolation theory.
Effects of tensile prestress level on Charpy impact value (a uc ) of 50 vol% continuous unidirectional 0 degree oriented carbon fiber reinforced epoxy polymer (CFRP) were investigated. Experimental results showed the a uc at mid-fracture probability P f = 0.50 induced by a large prestress of 17.6 MPa (109 kJm ¹2 ) was increased 30% over that (84 kJm ¹2 ) of slight prestress of 0.25 MPa. The statistically lowest impact value a s at P f = 0 calculated by 3-parameter Weibull equation was raised 26% from 73 to 92 kJm ¹2 showing increased reliability of part strength. Fracture surface observation showed a flat surface extending through the thickness from the impact side generally extends deeper as prestress level was raised. This may be due to the transition depth in the specimen thickness from compression to tension is deeper during impact as prestress level was increased acting to raise the impact values.
Influences of compressive and tensile stresses on an electrical resistivity of carbon fiber in polyvinyl acetate polymer on bending test are studied as a basic research to develop high sensitive stress sensors. It is confirmed that a compressive stress of less than 0.3 GPa on bending test reversibly decreases the electrical resistivity of carbon fiber due to enhancement of the density of state of bonding electron. A tensile stress of less than 0.3 GPa on bending test also decreases the electrical resistivity of carbon fiber, reversibly, because of decreasing the density of electron scattering sites.
To develop high temperature sensor, the change in an electrical resistivity of carbon fiber according to the stress increasing was measured as basic research. It was confirmed that the stress in the low stress zone decreased electrical resistivity, whereas the excess stress increased the electrical resistivity in the high stress zone.
Effects of electron beam irradiation on stress strain curves of glass fiber reinforced polymer (GFRP) have been studied. Electron beam (EB) irradiation decreases the resistivity (ds/de) of bending deformation of the GFRP. Although EB irradiation slightly decreases the maximum resistive stress on bending deformation (maximum bending stress), it also enhances the strain at the maximum bending stress. EB irradiation enhances the deformation energy to the maximum bending stress of GFRP. This energy mainly depends on not only the strain improvement at the maximum bending stress of epoxy resin and glass fiber, but also interfacial friction force.
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