초록
Preparation of thermoplastic composites is difficult since penetration of the thermoplastic resin into the reinforcing fiber is hindered by its high melt viscosity. Commingled yarn has been developed in order to overcome the difficulties that are experienced when impregnation is carried out with thermoplastic materials to prepare reinforced composite materials. Unidirectional composites were fabricated (150$\times$230 mm) by using commingled yarn consisting of glass fiber as the reinforcing fiber and nylon 6 as the matrix fibers. In this study, the longitudinal (0 $^{\circ}$), 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$, and transverse(90$^{\circ}$) bending strength were investigated by three point bending test. The relationships between the anisotropy of the bending strength and the holding time, molding pressure of 1st molding and 2nd molding thermoplastic composites were studied. The results were as follows 1. The bending stress for each direction is 53% at 30$^{\circ}$, 20% at 45$^{\circ}$, 14% at 60$^{\circ}$, and 8% at 90$^{\circ}$, to the fiber axis respectively. (At 0$^{\circ}$ the bending stress is 100%) 2. The bending stress of second molding product decreased about 10% and 25% when the direction is at 0$^{\circ}$ and 90$^{\circ}$, as compared with the first molding product.
