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Publisher Summary To illustrate different factors affecting the cost of textile composites, this chapter describes a cost modeling tool such that the process of cost estimation can be understood. It discusses cost build-up in textile composite applications, presenting a review of raw material prices. As the basis for examples presented throughout the chapter, it describes a cost prediction tool, which will drive an understanding of how cost is built-up in textile composite applications. This parametric Technical Cost Model (TCM) is based in MS Excel TM, interacting with MS Visual Basic TM. The TCM can be coupled with a discrete event-based Process-Flow Simulation (PFS) tool that dynamically represents the interactions between the different manufacturing operations. Hence, an averaging effect is gained over a statistically significant period, thereby generating input data for the TCM and increasing the accuracy of the cost calculation. The chapter also discusses the typical process machine and tooling costs, presents a summary of the effect of manufacturing volume on cost and the typical manufacturing volume of textile composite conversion processes. Assembly costs form important cost portions of a module and the chapter describes the effect of parts count reduction on cost. The chapter presents two case studies that show the build-up of system cost for components made of textile composite structures: (1) Chassis brace components produced by thermoplastic sheet stamping and over-injection molding and (2) Carbon epoxy aft fuselage panels for the Airbus A380.

Publisher Summary Thermoplastic composites offer increased recyclability and can be post-formed or reprocessed by the application of heat and pressure. A large range of tough matrix materials is also available. The manufacture of components from textile thermoplastic composites requires a heating process, either directly before the final molding process, where an oven plus a cool tool is used (non-isothermal processing), or in a hot mould (isothermal processing). Heat transfer forms the principal boundary condition governing process cycle times, with a corresponding potential for lower conversion costs. These basic steps define the many processing techniques that can be used to transform different material forms into the final product, where considerable flexibility exists to heat and shape the textile composites. One limitation for manufacturing techniques that result from the continuous, well-ordered, and close-packed fiber architectures is that these materials do not flow in the same way as a fiber suspension to fill a tool, but must instead be deformed by draping mechanisms. However, this limitation notwithstanding, a wide variety of both materials and processing techniques have been developed for both niche applications and components produced at high volumes. This chapter provides an overview of the impregnation and consolidation processes for thermoplastics that have driven both materials development and the choice of final conversion process. It presents a summary of thermoplastic composite pre-impregnation manufacturing routes and a review of final conversion processes for textile thermoplastic composites. The chapter also reviews forthcoming processing techniques for hybrid textile composite structures.

A blend consisting of equal amounts (by weight) of linear polyethylene and a technical grade of sodium lignosulphonate (a water soluble substance), was processed using hydrostatic extrusion with extrusion ratios varying from 5 to 20. The resulting extrudate contained thin (2 to 5μm) fibres of the linear polyethylene in a matrix of the lignosulphonate. The fibres were basically continuous throughout the extrudate. Their stiffness was of the same order as that observed for pure hydrostatically extruded polyethylene. The fibre phase was easily isolated by dissolving the matrix material in water.

High-pressure injection molding (nominal pressure 500 MPa) is known to substantially improve the mechanical properties of high-density polyethylene of a high molecular weight (HMWPE). This work shows that if the mold is equipped with an exit cavity, the tensile modulus and strength of HMWPE-bars molded is further improved at high pressure levels. The maximum values of the stiffness and strength (thin bars, 1 mm) obtained with the exit chamber is about 12 GPa and 260 MPa, respectively. The improvement due to the exit cavity is of the order of 30 percent for the tensile strength for thicknesses lower than 4mm, while the modulus increases about 1 to 1.5 GPa for bars with thicknesses between 1 and 6 mm. The orientation of the melt during the filling of the mold was also found to have an influence on the mechanical properties of the HMWPE bars.

In injection-moulded parts, the degree of orientation (anisotropy) varies over the cross-section. Normally, such parts exhibit a layered structure, with a biaxially oriented surface layer (stretching of the flow front during mould filling), a highly oriented shear zone, and a core region with a relatively low orientation. This paper describes a novel method to show the different morphological zones by studying the occurrence and structure of fibres formed during injection moulding of certain incompatible blends, in the present case a mixture of high-density polyethylene and a technical lignosulphonate grade (Wanin S). The polyethylene fibres formed during processing of this composite were ribbon-shaped in the surface layer (biaxial orientation), while they had a normal appearance in the shear zone. Only relatively few fibres were found in the core region. A qualitative agreement was found when the fibre character in the various layers was compared with orientation data from thermal shrinkage measurements, as obtained with pure polyethylene samples (test bars).

By increasing the injection pressure up to 500 MPa the modulus and the strength of injection moulded high molecular weight, high-density polyethylene (HMWPE) can be increased several times. In this communication the effects of processing conditions and mould design on mechanical properties of this type of high pressure injection moulded material are reviewed. It is shown that the use of high injection pressures can increase the modulus of the HMWPE to more than 10 GPa. Some results on the effect of adding carbon black to HMWPE are also included.

Blends of linear polyethylene with carbon black (1 and 10 wt%) and two low-molecular weight substances, camphor (10 wt%) and dimethylerephthalate (DMTP) (10 wt%), have been hydrostatically extruded under different conditions. Both camphor and DMTP were partly compatible with the polyethylene. Compared to an unfilled linear polyethylene, hydrostatically extruded under similar conditions, an increase in tensile strength is noted in some cases. This increase in strength may be accompanied by a decrease in stiffness. The composites containing the compatible substances could be processed at a significantly lower pressure level compared to the unfilled polyethylene.