Process and Equipment Description

The fibers are pulled from the roving and spread by a pneumatic device to facilitate polymer penetration. Then, in a deposition chamber, a thermoplastic powder is continuously supplied by a variable speed, double-screw miniextruder. By means of an air fan, the powder forms a cloud and adheres to the fibers. Three rolls conveniently placed inside the chamber increase the fibers path and, consequently, the deposition time and amount of adhering thermoplastic powder. Next, the fibers pass through a furnace to soften the polymer particles and promote their adhesion to the surface. Finally, the towpregs are cooled down and woundup on a spool with variable speed. 

This allows for a substantial saving of time in subsequent impregnation phases during processing. 

The typical coating line operational conditions are summarized in Table 2. 

PCT die temperature Furnace teip erature Coating chamber temperature Spreader pressure 

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