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A new titanium (Ti)/polycarbonate (PC) joint [Ti/EBCF/PC] internally connected by homogeneous low potential electron beam irradiation (HLEBI) activated cross-weave carbon ber (6 μm in diameter) cloth insert taking advantage of broad CF surface area had been developed. Applying HLEBI dose in the range of 0.043 to 0.43 MGy to the bare CF half-length prior to dipping in the thermoplastic PC molten resin enhanced ultimate tensile strength (σ b) of Ti/EBCF/PC over that without HLEBI [Ti/CF/PC]. The 0.30 MGy dose appeared to be near the optimum resulting in σ b of 20.7 MPa, an increase of 3.0, 3.9 and 21.1 times higher than that of Ti/CF/PC, with glue only [Ti/Glue/PC], and with spontaneous adhesion without glue [Ti/PC], at 7.00, 5.30, and 0.98 MPa, respectively. Moreover, regardless of HLEBI treatment, introduction of the CF insert into the joint prevented abrupt brittle fracture compared to the Ti/PC joint. The corrected ultimate tensile strength (c σ b) de ned as that of the 60 vol% CF-containing PC cross section portion calculated by rule of mixtures was also raised by the 0.30 MGy HLEBI to c σ b = 195 MPa (Ti/EBCF/CFRPC); 6.89 and 31.7 times higher than that of Ti/CF/CFRPC and Ti/PC at 28.3 MPa and 6.16 MPa, respectively. The HLEBI probably enhanced the ability to adhere the CFs to dif cult to adhere thermoplastic PC to generate the tremendously large friction force, with the aim of raising the safety level of lightweight material with high resistance to fracture for airplanes and automobiles.

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.

2-layer laminated sheets (PU/PET) with Polyurethane (PU) and Polyethylene Terephthalate (PET) were prepared by a new adhesion method, a double-step treatment consisting of applying low dose (≦ 1.72 MGy) homogeneous low energy electron beam irradiation (HLEBI) prior to hot-press under 3 MPa and 348 K. Although the weak hot-press adhesion of the PU/PET was observed without HLEBI, the new adhesion mostly raised the bonding energy as evidenced by the mean adhesive energy of peeling resistance ( o E p ). Based on the 3-parameter Weibull equation, the lowest o E p value at peeling probability (P p ) of zero (E s ) could be estimated. An increasing trend in E s occurred by the double-step treatment applying HLEBI up to 1.29 MGy reaching a maximum at 1.83 kJ·m, improving the safety level without radiation damage. When HLEBI cut the chemical bonds in PU and generated terminated atoms with dangling bonds, they probably induced the chemical bonding. Therefore, increasing adhesion energy between the laminated sheets could be explained.

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