Melt spinning flow through packs

The melt-spinning process used to convert mesophase pitch into fiber form is similar to that employed for many thermoplastic polymers. Normally, an extruder melts the pitch and pumps it into the spin pack. Typically, the molten pitch is filtered before being extruded through a multi-holed spinnerette. The pitch is subjected to high extensional and shear stresses as it approaches and flows through the spinnerette capillaries. The associated torques tend to orient the liquid crystalline pitch in a regular transverse pattern. Upon emerging from the... 

The dried polyester polymer is transported to extruders where it is melted, and piunped to spinning packs held in a spin manifold. The spin packs contain spiimeiets with a large number of fine holes through which the melted polymer flows to form filaments. Any contaminants in the polymer are removed by filtration prior to the spinneret. Different spinneret designs enable a wide range of fibre cross-sections to be produced including solid round, hollow and trilobal. 

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