Powder impregnated fibres

Compared to other intermediate product forms such as pre-impregnated tows or powder impregnated fibre bundles, commingled yams are attractive because they possess high flexibility, thus allowing the processing of complex shapes (Svensson et al., 1998). 

SUPreM, Plytron, Quadrax (Gurit Suprem) consolidated tapes or fabrics are made from continuous fibres impregnated with thermoplastic powder. The fibres can be glass, aramid, carbon, steel and the matrices are polyethylene, polypropylene, polyamide, PPS, polyetherimide, PEEK, thermoplastic polyimide, or fluorothermo-plastic. High levels of fibres can be obtained, 65% in volume, for example. 

Powder impregnation is a technique in which dry resin powder is applied to the fibres and normally then melt fused. The fibres are spread out mechanically or pneumatically. In various developments, the particles may be electrically charged the fibre tow can be passed through a fluidized bed and aqueous powder dispersions can be used. 

Powder impregnation Processing window can be large by selecting very different polymers Can be applied to commodity commercial polymer fibres or fabrics and powders Vf limited by matrix powder size Difficult to achieve good matrix distribution Usually uses more than one type of polymer... 

Squibs are cotton yams or other fibres impregnated with black powder and which bum with an external flame to ignite pyrotechnics, although the term may apply to small pyrotechnic or explosive devices. Safety squibs are those squibs which do not bum with an external flame. Electric squibs are essentially synonymous with the matchheads (bridgewire-low explosive combinations) used in electric detonators as well as a type of jet thmst igniter. 

The main disadvantage of thermoplastics is that their viscosity at the melt temperature is approximately two orders of magnitude greater than that of a thermoset. If the temperature is raised to aid fibre impregnation the polymer will be degraded. To overcome this various techniques are used based on film stacking, the use of powerful solvents or powdered polymer material. 

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