Fibres traditional Oriental

At 25 C, the powder precipitated from zinc sulphate solution was very heterogeneous, presenting some traditional morphologies, like half ellipsoids (250 nm x 350 nm) and ellipsoids (250 nm x 800 nm), both constituted by crystallites grouped in a preferential orientation, as well as 40-nm-diameter fibres of various lengths (Fig. 3a). The fibre structures for ZnO particles are usually synthesised by a thermal evaporation process [27, 28]. 

Processing is, of course, crucially important in determining nanotube dispersion and orientation, as well as the more traditional but equally important factors associated with polymer morphology. Polymer nanocomposite fibres may be spun from solution or from the melt, often following an initial dispersion step, as discussed in Section 7.3.1 above. Much of the initial work has been exploratory in nature, and there remains considerable scope for applying the wider understanding of fibre spinning to these systems. 

Studies of propylene random copolymers have recently gained importance over isotactic polypropylene in applications requiring high clarity, flexibility and low-temperature performance (Maier and Calafut, 1998). Traditionally, the enhancement in mechanical performance of melt-spun fibres relies primarily on the control of molecular chain orientation and crystalline structure development through take-up speed, drawing ratio and quenching conditions. Heterogeneous particulate reinforcement of polymers often leads to phase separation, increases the melt viscosity and creates hydrodynamic instabilities. 

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