Fibre intermingling

Fibre intermingling Processing window can be large by selecting very different polymers Good matrix distribution - no impregnation required Vf limited by matrix-fibre distribution Usually uses more than one type of polymer... 

Figure 4.76 displays two examples of modulus retention versus temperature for a neat and a glass fibre reinforced polycarbonate the two curves are practically intermingled with an abrupt fall at roughly 140-145°C. 

Specimens used for compressive strength measurements were prepared by a modified pultrusion process. Bundles containing carbon and HP-PE yarns in known proportions were immersed in a bath of epoxy resin and pulled into tubes with PTFE-inserts (6 mm internal diameter). Carbon and HP-PE yarns were intermingled as homogeneous as possible. The samples were cured for 4 hours at 80 C and then post-cured at 110 C for 12 hours. After curing specimens were removed from the mold and cut into 12 mm lengths using a low speed diamond saw. Volume fraction of fibres was held constant at 50% and the proportions of HP-PE fibre in the composite was varied from 0 to 100% with steps of 20%. 

The lay down system is required to intermingle the fibre bundles into a web of good coverage and uniform fabric weight. It is preferred to generate a single filament lay... 

Fig. 8 Consolidation of a self-reinforced polymer composite from a combination of arranged reinforcement fibres (dark grey) and matrix fibres (light grey). One row of fibres is shown normal to the plane of the page, although more complex fibre architectures can be arranged provided that matrix fibres can be suitably intermingled (a), the technique is equally applicable any arrangement of fibres such as woven fabrics and random fibre mats. The intermingled matrix fibres are forced to melt and flow around the fibres by the application of heat and pressure and thus, on cooling, the fibres remain embedded in a matrix from the re-solidified matrix fibres (b)...

In the case of nanotubes, several techniques were proposed functionalization by organic molecules [1] and the use of surfactants like sodium dodecyl sulfate (SDS) to disperse them in water. This kind of dispersion led to the manufacture of fibres made of nanotubes [2]. Nanotubes can also be cut to avoid their intermingling and thus improving their dispersion. 

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