Continuous Fiber-Reinforced Thermoplastics

Autoclave molding, the process of curing thermoset resins at elevated temperature and pressure in an inert environment, has an important role in the fabrication of continuous fiber reinforced thermoplastics. While most companies view thermoplastics as an alternative to traditional autoclave long-cycle processing, they have come to accept the following reasons for the autoclave processing of thermoplastic matrices ... 

High production rates can be achieved using thermoforming technology. However, it is difficult to form high quality continuous fiber reinforced thermoplastic parts with demanding geometries, due to the restricted movement of the fiber. 

T Asai, T Ohara, T Tanaka, S Hashizume. Method of Manufacturing Continuous Fiber-Reinforced Thermoplastic Prepregs. U.S. Patent 5529652, June 25, 1996. J-M Charrier, PJ Bates, D Guillon, G Zanella. The Effect of Pin Shape on Spreading Roving Filaments for a Thermoplastic Pultrusion Process. 45th Annual Conference, Composites Institute, SPI, Washington DC, 1990, 18-A, pp 1-4. 

E)ykes, R.J., Horrigan, D.P.W. and Bhattacharyya, D. (1997) Numerical analysis of shape fixability of continuous fiber reinforced thermoplastics. Proceedings of the Eleventh International Conference on Composite Materials, ICCM-II, Vol. 9,... 

Dykes R J, Mander S J and Bhattacharyya D (2000) Roll Forming Continuous Fiber-Reinforced Thermoplastic Sheets Experimental Analysis, Composites Part A 31 1395-1407,... 

This section focuses on continuous fiber-reinforced thermoplastic materials and the molds that are needed for a high-volume-compatible production of these materials. The complete process chain is illustrated in Figure 1.214. 

As seen in Figure 1.215 to Figure 1.217, processing of continuous fiber-reinforced thermoplastic materials is done in heated molds. These are mostly manufactured from mold steels for warm processing (so-called hot work steels). Well suitable steels are for example 1.2311,1.1730, and 1.2710. A useful help for selecting the appropriate mold steel is the so-called Key to Steel (Stahlschliissel Verlag, Marbach, Germany). Different steels and their composition and suitability are therein defined. 

Diaphragm forming is one of the oldest processing procedures for the manufacture of thin-walled components made from continuous fiber-reinforced thermoplastic materials. The non-isothermal diaphragm forming established itself. It has shorter cycle times than diaphragm forming in an autoclave [8, 9]. 

Again, matched-mold thermoforming is recommended. Long- and continuous-fiber-reinforced thermoplastics pose an additional processing problem. Alliiough the reinforced sheet can be drawn into shallow shapes using matched-mold pressure forming, fibers are inextensible. As a result, products will exhibit resin-rich and resin-poor areas. Nonuniformity in reinforcement implies nonuniformity in physical properties across the product. 

Pellet Production Technology of Continuation Fiber-Reinforced Thermoplastic Resin Composite Material... 

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... 

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