Abstract
In the automobile industry, carbon fiber reinforced thermoplastics (CFRTP) have attracted attention as potential materials to reduce the weight of the automobile body. In order to apply CFRTP to mass-produced automobile parts, it is necessary to develop the reduction of molding time and the impregnation method into the carbon fiber (CF) for the thermoplastic resin, which has relatively high viscosity. Although the conventional hot press molding uses only the heat transfer from the mold to the molding materials, it is expected to develop a new molding method for CFRTP using heat generation of the materials themselves to overcome these issues. As a method of heating the carbon fiber, there is a direct resistance heating method, in which carbon fiber is directly energized and heated by Joule heat. We have developed resistance welding methods in which carbon nanotube (CNT) grafted carbon fiber (CNT-CF) is used for the heating elements, and revealed that the higher welded strength is obtained by using CNT-CF instead of CF. Therefore, the carbon nanofilaments (CNF) grafted carbon fiber (CNF-CF) including CNF-CF is expected not only to be used as a resistance heating medium at the time of joining but also as a reinforcing fiber and as a self-heating member at the time of molding. In this study, we develop the CFRTP molding method by using direct resistance heating to CNF-CF in the hot press molding. CFRTP ([0°]20) with the volume fractions (Vf) of 40% are molded by conventional hot press and hot press with direct resistance heating to reinforcing fiber. CF or CNF-CF is used for reinforcement. CFRTP molded by hot press with direct resistance heating to CNF-CF indicated lower void content than CFRTP molded by hot press with direct resistance heating to CF. Compared to CFRTP molding by only hot press, hot press molding with direct resistance heating to CNF-CF can mold CFRTP with low void content.
Highlights
In the automotive industry, from the strict regulation of CO2 exhausted from automobiles, it is necessary to reduce the weight of the automobile body [1]
In order to apply carbon fiber reinforced thermoplastics (CFRTP) to mass-produced automobile parts, it is necessary to develop the reduction of molding time and the impregnation method into the carbon fiber (CF) for the thermoplastic resin, which has relatively high viscosity
We have developed resistance welding methods in which carbon nanofilaments (CNF) grafted carbon fiber (CNF-CF) is used for the heating elements, and revealed that the higher welded strength is obtained by using CNF-CF instead of CF [19]
Summary
From the strict regulation of CO2 exhausted from automobiles, it is necessary to reduce the weight of the automobile body [1]. In order to apply CFRTP to mass-produced automobile parts, it is necessary to develop the reduction of molding time and the impregnation method into the carbon fiber (CF) for the thermoplastic resin, which has relatively high viscosity. We have developed the molding method and bonding method of CFRTP using direct resistance heating to carbon fiber [7,8]. Carbon nanofilaments (CNF), including carbon nanotube (CNT), have excellent mechanical, electrical, and thermal properties Their application to composite materials is attempted using various methods. Carbon nanofilament (CNF) grafted carbon fiber is used for the self-heating member, and the effect of direct resistance heating and CNF grafting to the carbon fiber surface on the impregnation properties of CFRTP are discussed
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