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Thermoplastic resins used as a matrix of fiber reinforced thermoplastics (FRTPs) are composed of high polymers that remain highly viscous even at a higher temperature than their melting points. As a result, they need an even higher temperature, a higher pressure and a longer processing time to allow them to bond with fibers that require large and specialized equipment. In contrast, fiber-reinforced thermoset plastics (FRPs) can be easily molded owing to the use of lower viscosity liquid resin as the matrix using simpler devices. In this paper, a new fabrication method of FRTPs using in situ polymerizable ε caprolactam as the matrix is presented. This method uses vacuum-assisted resin transfer molding without the need for large and specialized equipment. The ε-caprolactam molecules were converted from their monomer form into a polyamide 6 resin, with ring-opening polymerization of ε-caprolactam during the molding process at a lower temperature than its melting temperature. The two kinds of FRTPs obtained using ε-caprolactam as the matrix had neither voids nor unfilled parts because ε-caprolactam had a very low viscosity before the polymerization. These FRTPs not only exhibit superior bending properties but also are suitable for high-speed molding, namely, within a few minutes of process time.

Hemp fiber-reinforced green composites with organoclay-filled poly(butylene succinate) (PBS) matrix were fabricated by pultrusion process. Morphological studies revealed that the clay particles were intercalated/partially exfoliated when the clay content was lower than 6 wt%. The tensile modulus and strength of PBS/25% hemp composites were 15 and 2.9 times of the neat PBS. By adding organoclay to the PBS/hemp composites, the tensile properties of the hybrid composites generally reflected the similar change with the organoclay modified PBS matrix. Upon certain duration of environmental exposure, the degradation of tensile properties of hemp/organoclay/PBS hybrid composites was retarded compared with hemp/PBS composites.

In 1981, many detached houses collapsed owing to the earthquake which took place at the coast of Miyagi Prefecture in Japan, because ferroconcrete was not used as the base of most of the collapsed houses. Therefore, the earthquake-proof design criterion was revised and it was obliged to use ferroconcrete as the base of detached houses ever since. However, there are still more than 10 million detached houses using aged concrete as the base in Japan. In this paper, a reinforcement method for the aged concrete is demonstrated by using the high performance carbon fiber reinforced plastic (CFRP) strips. Three kinds of concrete beams reinforced with the CFRP strips with different vertical insert positions and different numbers of the CFRP strips were tested by a four point bending test method. In order to clarify the effects of CFRP strips, a concrete beam without reinforcement was also tested. The results of the experiment showed that the maximum deflections of the concrete beams reinforced with the CFRP strip were more than 100 times larger than those of the concrete beams without reinforcement. Although the concrete beams without the CFRP strips collapsed instantly, the concrete beams reinforced with the CFRP strips gradually failed, which were similar to the plastic behavior of metals. This result means that the residents can afford to escape safely from the houses in the event of possible earthquakes. The experimental results were compared with the analytical ones obtained from the composite beam theory and the failure criterion. Both results showed good agreement and the effectiveness of base concrete reinforced with CFRP strips was demonstrated.

This paper describes an optimum structural design of a CFRP isogrid cylindrical shell using a genetic algorithm (GA). When the CFRP isogrid cylindrical shell receives a prescribed uniaxial compressive load, an objective is to minimize weight of the CFRP isogrid cylindrical shell subjected to the constraint conditions of no buckling and no material failure. The buckling and material failure loads were approximated by a response surface method combined with partitioning of design spaces and these approximated values were used in the process of GA instead of FEM calculations in order to reduce the computational time. Furthermore, the differences from the constraint conditions of the linear or the non-linear (local) buckling loads were also calculated and their results were compared with each other. [ABSTRACT FROM PUBLISHER]