Powder-impregnated yarns

To overcome the drawbacks of preimpregnated tape or film stacking, intermediate fibers for continuous fiber-reinforced thermoplastic composites have been developed. Intermediate fibers have flexibility and are developed for textile appH-cations. As shown in Figure 10.14, the powder-impregnated yarn contains fibers impregnated with fine thermoplastic particles [12-16]. The incorporation of the matrix powder into the reinforcement yarn is performed by the fluidized-bed... 

Figure 10.14 Schematic drawing of powder-impregnated yarn.

Safety fuses are used for the direct ignition of propellants, pyrotechnics, and primary explosives. A safety fuse is composed of a black powder core, three layers of cotton or jute yarn wound around the core, bitumen impregnation, and plastic coating. The burn rate for a safety fuse is usually around 120 + 10 seconds/meter. 

The length of the fuse will depend on the safety period required. The structure of the fuse comprises (proceeding from the fuse interior outwards) a black powder core with one or two marking threads, the color of which indicates the identity of the manufacturer, two or three layers of yarn wound around it (jute, cotton, or some other yarn), a bitumen impregnation, and a plastic coating. 

Nonreactive thermoplastic pultrusion utilizes completely polymerized plastics in various preprocessed states such as powder, granulates, filaments, or solutions. The use of preimpregnated fibers is advised due to short flow paths. These preimpregnated fibers can be fed into the pultruder as commingled yarns, thermoplastically coated yarns or tapes. Since impregnation is already done, no impregnation device is needed. Instead, due to the low thermal conductivity of the matrix material and its limited deterioration temperature. 

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