Tensile strength at each accumulative probability of strength (Pf) was obtained for 28mass% carbon fibers (CF) reinforced thermoplastic polypropylene (PP) with and without sizing epoxy film on the fibers prior to making composites (CFRTP) of three cross CF cloth sheets and four PP matts, layer by layer. The sizing film covered on CF apparently improved the tensile strength. Namely, an effect of the sizing epoxy film covered on carbon fiber apparently strengthened the CFRTP. It could be explained by the increasing resistance to pull-out fibers with large friction force because the adhesive sizing film probably increased the interface contact atom pairs of CF and PP. The PP was distorted and twisted polymers more than that of straight polymers of polyethylene, and was probably generated the spontaneous nano-scale rough interface against CF.
The homogeneous and quick treatment of 100 keV class electron beam irradiation (EBI) improved the resistance to impact fatigue indicated by the critical collision number (N c) of impact fracture of PZT (Pb(Nb 2/3 Ni 1/3)O 3-Pb(Zr 1/3 Ti 2/3)O 3) ceramics, although an additional dose decayed them. An optimal dose of 0.086 MGy-EBI apparently improved the N c and E C i of PZT. It could be explained by shortening the lattice constant after the collision for the PZT irradiated with the optimal dose.
Applying low-potential electron beam irradiation (EBI) dose of 0.13 MGy to polycarbonate (PC) sheet on both side surfaces apparently improved the impact value (a uc ) over the untreated samples at all accumulative probabilities of fracture (P f ). Based on 3-parameter Weibull equation, the 0.13 MGy-EBI also raised the lowest limit of a uc (25.5 kJ m ¹2 ) estimated at P f = 0 (a s ) 14% over the untreated samples (22.0 kJ m ¹2 ), indicating improved reliability and safety. EBI generates dangling bonds where repulsive forces are generated between the outer shell electrons at terminated atoms in the PC polymer irradiated near the sample surface, probably inducing relaxation of heterogeneous stress concentration, as well as compressive stress (high molecular density) by micro-expansion around terminated atoms increasing the a uc . Increasing EBI dose increased ductility by decreasing the fractured split ratio, R s a characterization of separated portion of total cross-section of fractured PC. The 0.13 MGy dose (R s = 0.30) appears to be at or near the optimal EBI dose obtaining the highest a uc . Above 0.22 MGy the a uc reduces with increasing dose. Excessive dangling bonds generation appeared to increase ductility in the form of lowering the R s but weakens the molecular structure allowing chains to slide past each other easier decreasing impact values with less crack propagation. Therefore, when applying EBI to polycarbonate parts in industrial applications carefulness is highly recommended to adjust dose to optimal level for maximum strength and safety.
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