| abstract |
The purpose of the present invention is to provide a fiber-reinforced composite material which comprises reinforcing fibers and a thermoplastic resin, can exhibit excellent mechanical properties even when formed in a small thickness, and enables the provision of an isotropic molding.nThe present invention is a reinforcing fiber composite material comprising reinforcing fibers each having a fiber length of 5-100 mm and a thermoplastic resin, and characterized in that the average value for a viscoelastic property which is defined by formulae (1) and (2) at a temperature up to 25˚C higher or lower the melting point of a matrix resin fulfills formula (3).ntanδ = G''/G' (1)ntanδ' = Vf×tanδ/(100-Vf) (2)n0.01 ≤ tanδ' ≤ 0.2 (3)n(In the formulae, G' represents the storage elastic modulus (Pa) of the reinforcing fiber composite material; G'' represents the loss elastic modulus (Pa) of the reinforcing fiber composite material; and Vf represents the volume fraction (%) of the reinforcing fibers in the reinforcing fiber composite material.) |