Thermoforming of fiber-reinforced composite sheets

The potential advantages of rapid component manufacturing using FRTP sheets and associated reduction in production costs can be of tremendous benefit to various industries. These advantages arise from (1) the 

Under the general description of thermoplastic composite sheet, a number of material options exist with various forms of fibers (e.g. unidirectional, mat, knitted, woven, chopped strand, etc.) reinforcing a thermoplastic pol)oner matrix. Further to the differences in their 

Cogswell, F.N. (1992) Thermoplastic Aromatic Polymer Composites, Butterworth-Heinemann, Oxford. 

Martin, T.A., Bhattacharyya, D. and Pipes, R.B. (1992) Deformation chciracter-istics and formabUity of fiber-reinforced thermoplastic sheets. Composites Manufact., 3, 165-172. 

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This process has been developed specifically for thermoplastic composite plate materials. But it is also well suited for commingled fabrics, especially when they are pre-consolidated by the use of a double belt press into continuous organic sheets [8]. Further details about the thermoforming procedure are described in the chapter Thermoforming of fiber reinforced composite sheets. 

With regard to methods of fabrication, all processes in Table 1.1 that are applicable to unfilled, unmodified thermoplastics can also be used for discontinuous systems (with the exception of expandable bead molding). In addition to thermoforming, hot stamping of reinforced thermoplastic sheets mostly containing randomly oriented continuous or discontinuous fibers is used for the production of large semistructural parts. Fillers can also be used in the thermoset processes in Table 1.1, often in combination with the primary continuous fiber reinforcement. The content and inherent properties of the additive, as well as its physical/chemical interactions with the matrix, are important parameters controlling the processability of the composite. 

The main stream of wood fiber PP composites is short fiber reinforced, suitable for typical thermoplastic processing. The main steps of this technology are (1) pre-mixing, (2) plastic transformation of the melt (typically sheet extrusion), and (3) thermoforming (vacuum- or pressureforming) of the sheet. 

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