Influence of contents rate and dispersion of carbon nanotubes on interfacial adhesion between continuous fiber reinforced thermoplastics and injection resin

Fiber reinforced plastics have been expected as an alternative of metal materials in order to reduce the lightweight of the automotive and the environmental loading. Carbon fiber reinforced thermoplastics (CFRTP) have been studied from the view point of reducing cycle time and recycling of polymer materials. Prepreg compression molding (PCM) enables to provide the excellent mechanical property. However, PCM is difficult to form complex shape. On the other hand, hybrid injection molding (HIM) has attracted attention because HIM makes it possible to form complex shape. However, the mechanical property of molded parts are affected by the interlaminar shear strength between continuous fiber reinforced thermoplastics and injection molded parts. Some researchers reported interlaminar shear strength improve by use of carbon nanotubes (CNTs). Therefore, we aimed at improving interfacial adhesion by preparing a film with CNT added in matrix and inserting the film at the interface of hybrid injection molded parts. We conducted short beam test on specimens inserted films. When CNT/PP film was used, the interfacial shear strength was improved compared to when no film was used. When the CNT was in the low dispersion state, the interfacial shear strength rose gently up to 1.0 wt% and dropped greatly at 3.0wt%. On the other hand, when the CNT was in the highly dispersed state, the interfacial shear strength rose up to 0.5 wt%, and thereafter dropped. When the CNT content was 1.0 wt%, the CF entered deep into interface at low dispersion. However, the interface was smooth and entry of CF could not be confirmed on the peeled surface at high dispersion. There is an optimum value for the content and dispersibility of CNT in the film.