Fibre-reinforced thermoplastic composites processing

Damage tolerance of fibre reinforced thermoplastic composites Processing of polymer matrices using resin transfer moulding Fractal analysis of wear in short-fibre reinforced thermoplastic composites Rheology flow behavior of associative polymers in coating applications Kevlar-thermoplastic composites... 

Short fibre reinforced thermoplastic composites can be processed by most of the classical thermoplastic processing techniques, such as, extrusion and injection moulding. A detailed discussion is provided for these classical thermoplastic processing techniques in Section 9.1. 

Barnes, J.A. and Cogswell, F.N. (1989) Transverse flow processes in continuous fibre-reinforced thermoplastic composites. Composites, 20(1), 38-42. 

Zampaloni, M., Pourboghrat, F. and Yu, W. (2004), Stamp thermo-hydroforming A new method for processing fibre-reinforced thermoplastic composite sheets . Journal of Thermoplastic Composite Materials, 17, 31-50. DOI 10.1177/0892705704038219. 

F. G. Torres, and R. M. Diaz, Morphological characterisation of natural fibre reinforced thermoplastics (NFRTP) processed by extrusion, compression and rotational moulding. Polymers Polymer Composites 12 (8), 705-18 (2004). 

Processing of LFRT or LFT - long fibre (reinforced) thermoplastics injection, composite insert moulding, compression moulding, extrusion-compression. 

Traditional processes can be modified to better industrialize the manufacturing of medium- or short-run manufacturing. In the thermoplastic composite field, the Pressure Diaphorm Process allows the processing of continuous fibre reinforced thermoplastics with low pressures. The press and the moulds (wood, composite or aluminium) can be about 70% cheaper. The process is convenient for short and medium runs in the range of 1000 up to 100000 parts. 

Compounds are short (/w 0.3 mm) or long (> 0.6 mm) fibre reinforced thermoplastic or thermoset polymeric materials, which are processed automatically (injection or compression moulding), have good (mechanical) properties (for automotive, electric and electronic applications) and are relatively cheap. Composites contain continuous fibres (rovings, fabrics or mats), usually combined with thermosets, have excellent mechanical (structural) properties, but are very expensive because lack of an industrial process (mainly used in aerospace and aircraft industry). 

HTPC (Hybrid ThermoPlastic Composite) bumper beams made by Plastic Omnium are used by General Motors on the Pontiac Montana, Chevrolet Venture and Oldsmobile Silhouette. Continuous woven fibres are overmoulded with a long or short fibre reinforced polypropylene to save weight (6 kg), enhance impact resistance (20-40%) and integrate numerous functions such as reinforcement ribs. The process is fully automated. 

These thermoplastics can be processed in nanocomposites and fibre-reinforced composites. 

Extrusion and injection-moulding are the economically most attractive processing methods of thermoplastic-based composites. The extrusion press processing (express-processing) has been developed for the production of flax fibre reinforced PP at the research centre of Daimler Benz [7]. In this process, flax fibre non-wovens and PP melt films are alternatively deposited and moulded. A production process for PP semi-products reinforced with lignocellulosic fibres in the form of mats has been developed by BASF AG [7]. Fibre mats are produced by stitching together layers of fibres which have previously been crushed. 

Van de Velde K, Kiekens P (2001) Thermoplastic polymers overview of several properties and their consequences in flax fibre reinforced composites. Polym Test 20(8) 885-893 Van de Weyenberg I, Ivens J, De Coster A, Kino B, Baetens E, Verpoest I (2003) Influence of processing and chemical treatment of flax fibers on their composites. Compos Sci Technol 63 (9) 1241-1246... 

The lower thermal stability of natural fibres (up to 230 °C), limits the number of thermoplastics to be considered as matrix material for natural fibre thermoplastic composites. Only thermoplastics whose processing temperature does not exceed 230 °C are useable for natural fibre reinforced composites. These are, most of all, polyolefines, like PE and PP. Technical thermoplastics, like polyamides, polyesters and polycarbonates require processing temperatures >250 °C and are therefore not useable for such composite processing without fibre degradation. 

Hou M, Ye L, Mai Y-W. Advances in processing of continuous fibre reinforced composites with thermoplastic matrix. Plast Rubber Compos Process Appl 1995 23 279-93. 

The fracture estimation of composites based on thermoplastic matrix reinforced with short fibres represents a complex problem, even in the case of the unidirectional composites supposed to a traction effort on the fibres direction, since the process can occur at interface, in fibre, or in matrix, respectively. In addition, the matrix should suffer the fracture by tensioning or shearing. 

---