MECHANICAL PROPERTY AND CRACK PROGRESSION BEHAVIOR OF LONG FIBER REINFORCED THERMOPLASTIC COMPOSITES

摘要

There has been an increasing interest in the use of thermoplastic matrices in long fiber reinforced composites. Thermoplastic resin has been widely used because of the excellent properties such as high fracture toughness, high impact performance, short molding cycle time, the ability to be re-molten and re-processed and high potential for significant reduction of manufacturing cost. However, the main problem with using thermoplastic matrices for long fiber reinforced composites is the difficulty in impregnating the high melt viscosity resin into the reinforcing fiber bundles. In order to overcome this difficulty, various intermediate materials have been developed, for example, commingled yarn [1] and powder coated yarn, and so on. These intermediate materials have excellent impregnation properties. One of the superior points of thermoplastic composites is that the selection window for a suitable material is very wide. From the viewpoint of mechanical properties, there are many thermoplastic materials that possesses either ductile or brittle characteristic, which means that various mechanical property can be obtained. However, only limited combinations of reinforcing fiber and matrix resin are available for the above-mentioned intermediate materials. Moreover, commingled yarn can be easily damaged during intermingling process.