Figure 1. Cross-sectional photomicrograph of
a 16-segment splittable fibre [20].
c) Direct spun type
This microfibre is directly manufactured by melt spinning. For this method, highly selected
polymerisation, polymer, spinning conditions, and drawing conditions are required [2].
Special melt spinning dynamics should be considered for the production of low linear density polyester
by the direct extrusion method. When polymers have similar dynamic viscosities at the given
temperature, the polymer with the lower dynamic viscosity permits the spinning of finer fibres. This
result has been attributed to the lower spin-line tension generated when spinning polymers with lower
dynamic viscosity. It is postulated that the important parameter in the production of finer PET fibre is
the spin-line tension level, which must be kept low in order to obtain finer fibres. The increase in takeup
velocity, and the fibre line length beetwen the spinnered and the take-up device increase the spinline
stress level, and therefore the minimum fineness attainable increases.
There are the following areas where microfilament spinning requires care: