Short Fibre-Reinforced Thermoplastics Composites

Tsai, S.W. and Hahn, H.T. Introduction to Composite Materials, Technomic Westport, CT (1980). Folkes, M.J. Short Fibre Reinforced Thermoplastics, Research Studies E ress, Somerset (1982). Mathews, F.L. and Rawlings, R.D. Composite Materials Engineering and Science, Chapman and Hall, London (1993). 

Future prospects for thermoplastics and thermoplastic composites 7.5.5 Short fibre reinforced thermopiastics to compete with LFRT... 

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. 

Sato N., Kurauchi T., Sato S. and Kamigaito O. (1983). SEM observation of the initiation and propagation of cracks in a short fibre reinforced thermoplastic composite under stress. J. Mater. Sci. Lett. 2, 188-190. 

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... 

Thermoplastics offer a wide variety of properties ranging from the low intrinsic stiffness and high design freedom of neat and short fibre reinforced thermoplastics to the high intrinsic stiffness and low design freedom of continuous fibre reinforced thermoplastic composites. Different polymeric... 

Folkes MJ, Short Fibre Reinforced Thermoplastics, Research Studies Press, Letchworth, 1982. Bigg DM, Characteristics of short, conductive fibre reinforced injection mouldable composites, J. Ind Fabrics, 2(3), 4-14, 1983-1984. 

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. 

To maximise the mechanical properties of short fibre-reinforced thermoplastic composites, it is necessary to achieve effective stress transfer between fibre and polymer matrix and appropriate fibre alignment in the finished component relative to the direction of applied stress. The former requirement is governed primarily by the method of compounding, whilst fibre orientation is very dependent on moulding conditions [76]. 

Lucintel, a global market research firm, has studied the sector. They reviewed the global short fibre reinforced thermoplastic composites market and estimated that the sector could reach approximately 5.99 billion by 2019 [4]. 

The data bands for short length fibre thermoplastics and long fibre reinforced thermosets lie adjacent to one another with a similar shape if the fatigue data for each composite is divided by the ultimate strength (Table 10.3). 

Mlekusch, B., Lehner, E. A. and Geymayer W., Fibre orientation in short-fibre-reinforced thermoplastics I. Contrast enhancement for image analysis. Composites Science and Technology, 59, 543-545 (1999). 

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. 

A solid structural substance produced by a combination of two or more materials that retain their identities. Typically, one of the materials combined is the strengthening agent, the other being the matrix (a thermoset or a thermoplastic resin). The word composite is also used for systems that are reinforced (reinforced where cumulative properties are superior to the individual components) by addition of certain solid particles (i.e., short fibre composites - long fibre composites - continuous fibre composites). 

Hitchen SA, Ogin SL, Smith PA, Soutis C, The effect of fibre length on fracture-toughness and notched strength of short carbon-fibre epoxy composites. Composites, 25(6), 407-413, 1994. Kishimoto K, Notomi M, Koizumi T, Fracture toughness of short carbon-fibre-reinforced thermoplastic pol5mide. Engineering Fracture Mechanics, 49(6), 943 et seq, 1994. 

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). 

The static fracture of the composite materials with thermoplastic matrix reinforced with short fibres... 

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. 

Static fracture of the composite materials with thermoplastic matrix and unidirectional reinforced with short fibres H.L. Cox firstly treated, a case of fibre/matrix interaction, of elastic/elastic type, without taking in consideration the fibre ends. He found the fracture s determinant component is that characterised by the smallest/weakest deformation [1276]. This approximate... 

Dynamic fracture (by fatigue) of the composite materials with thermoplastic matrix and reinforced with short fibres In this field, the investigations were devoted to elucidate the polymer and composite materials behaviour under exploitation conditions (non-notched specimens) as well as regarding the crack propagation (notched specimens). In the first place, the attention was focused on the composite materials with thermoreactive matrix, widely used in the automobiles industry. The test results, performed... 

The modelling of the endurance of the thermoplastic materials reinforced with short fibres was mainly realised in the form of empirical equations, based on concrete experimental data [1296], The typical endurance curves for glass or carbon fibres reinforced nylon 6,6 are depicted in Figure 3.459. A normalised representation, with respect to shows that the degradation ratio of the composite material is 10%, irrespective of the nature of investigated material [1296]. 

The fibres orientation with respect to the stress direction essentially influences the fracture mechanism, as it was proved for a composite with semicrystalline matrix, PET reinforced with short fibres, having the structural characteristics presented in Figure 3.496 [1267], It can be observed that different fibre orientation normally exists across the thickness of injection moulded plaques of short fiber reinforced thermoplastics. 

So far when considering carbon fibre composites the matrix has been a thermosetting resin or polymer. The relative merits of thermosetting and thermoplastic polymer matrices were discussed briefly in Chapter 3. Several thermoplastic matrices are compounded with short carbon or glass fibres. In Table 5.22 however the properties of unidirectional, continuous, carbon fibre-reinforced materials are illustrated. 

Most biodegradable composites being tested employ a thermoplastic matrix. There are inherent difficulties in interfacial wetting between linear thermoplastics and reinforcing fibres which limit optimum stress transfer between the fibre and matrix. This also deleteriously affects hydrolytic stability [63]. While the use of solid polymer without fibre has been considered [24,71-73], problems such as premature cracking can occur. Short fibre composites have been made and tested [63], but properties are not optimal. 

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