Commingled yams

Another important application of thermoplastic fibers such as poly ether ether ketone (PEEK), Poly etherimide(PEI), and VectranM andHS (Vectranis the trade mark of Hoechst liquid crystalline polymer) is in making thermoplastic matrix composites. Commingled yams of the reinforcement and matrix such as quartz/PEEK, glass/PEI, Vectran HS/M are used to make the composites wherein the matrix yarn fuses to form the continuous phase of the composite. 

More fundamental studies with the material under special consideration here, i.e. GF/PP commingled yams or fabrics, were thoroughly preformed with regard to its isothermal consolidation behavior and to an optimization of its flexural stiffness by Cain et at. [6]. In the following, some further details about impregnation, consolidation and resulting properties of GF/PP will be discussed. 

Various processing routes typical for thermoplastic composites of direc-tionalized reinforcements are also open to commingled yams or prepregs of them. 

Hamada, H., Maekawa, Z.I., Ikegawa, N. and Matsuo, T. (1993) Influence of the impregnating property on mechanical prop>erties of commingled yam composites. Polymer Composites, 14(4), 1993, 308-313. 

In the following section, some new data on the pultrusion of glass fiber/PP fiber commingled yam are presented and compared to results of previous investigators. 

Kejtwords pultrusioir, mechanical properties, glass fiber, void content, commingled yam, modelling, processing window, impregnation, Darcy s law, composite profiles, composite tubes. 

Compared to other intermediate product forms such as pre-impregnated tows or powder impregnated fibre bundles, commingled yams are attractive because they possess high flexibility, thus allowing the processing of complex shapes (Svensson et al., 1998). 

A cost-effective solution to the automotive industry using composites made of commingled yams can be given on the material combination of glass fibres and polypropylene (Thanomsilp and Hogg, 2005 Thanomsilp and Hogg, 2003)... 

D warp interlock fabrics, constituted by commingled yams, can be preformed at room temperature and this cool forming tends to be better controlled and seems to be more economical (Vanclooster et al., 2009a,b Padvaki et al., 2010 Thomanny and Ermanni, 2004 Zhu et al., 2011). The increase of temperature and the resin consolidation phases after the forming can be achieved under isothermal conditions thanks to a closed mould. By this way, it appears easier to avoid defects during the non-isothermal thermoforming process, especially for thick preform. 

However, to check the forming behaviour of 3D warp interlock made with commingled yams, using such a complex final preform as represented in Figure 10.6, a first approach is applied on different fabric parameters and forming shapes to find the best adapted architecture to the stamping process. 

Considering the three selected weave diagrams. E-glass and polypropylene commingled yams of 360 Tex linear density have been used as shown in Table 10.1. The initial thickness of these three selected architectures, as mentioned in Table 10.1, corresponds to the measurement done on the flat fabric out of the loom. 

According to the automotive manufacturer requirements to use a commercial existing reference of thread, a new commingled yam has been selected to perform this optimization. Thus, 3D layer-to-layer warp interlock fabrics have been made with 1100 Tex Twintex yams (commingled E-glass and polypropylene yam). 

However, using new commingled yams and new gusset shape leads to a higher and non-equilibrated consumption of 3D warp interlock fabrics during the forming process. 

Svensson, N., Shishoo, N., Gilchrist, M., 1998. Manufacturing of thermoplastic composites from commingled yams - a review. J. Thermoplast. Compos. Mater. 11 (1), 22-56. 

Thanomsilp, C., Hogg, P., 2003. Praietration impact resistance of hybrid composites based on commingled yam fabrics. Compos. Sci. Technol. 63, 467-482. 

Thomanny, U., Ermanni, P., 2004. The ittfluence of yam structure and processing conditions on the laminate quahty of stampformed carbon and thermoplastic polymer fiber commingled yams. J. Thermoform. Compos. Mater. 17 (3), 259-283. 

Risicato, J.-V., KeUy, F., Soulat, D., et al., 2015. A complex shaped reinforced thermoplastic composite Part Made of commingled yams with integrated sensor. Applied Composite Materials 22 (1), 81-98. 

A complex shaped-reinforced thermoplastic conq>osite part made of commingled yams... 

Tensile tests (NF-EN-ISO 2062) were conducted on 20 commingled yam specimens in order to ensure their compatibility with the load tension applied during the braiding process. The results are given in Table 16.1. Tensile properties are almost exclusively brought to the composite by the glass reinforcement. 

The textile architecture made of the braided commingled yams were heated and pressed in order to melt the PP matrix and form the composite stmcture with G reinforcement. The consolidation process greatly influences the composite performance [37] but is... 

Due to manufacturing parameters, the resulting plates differed in terms of their area density. The measured area densities are given in Fig. 16.8 and are compared with their thicknesses. It is important to clarify that no matrix of the braided preforms is lost during the manufacturing process. Consequentiy, the fibre volume fraction of the samples is equivalent to the fibre volume content in the raw commingled yam 44%. The thickness is directiy linked with the area density due to the constant density of the global material. 

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