Abstract
It has been considered that it is difficult to obtain a fine denier fibre from polypropylene by general method of melt spinning, used for nylon, because of its high viscosity in molten state.
However, polypropylene raise molecular degradation at 250°C or over, and then adequate melt viscosity for spinning can be obtained, so that after melting for suitable hours at 250°C or over, fine denier fibre may be spun by melt spinning machinary equiped with a gear type metering pump.
In spinning process, the properties of the drawn fibre is independent of the time for which the polymer is held molten in broad time range, therefore also with the molecular weight. The spun yarn possesses a high breaking elongation (several hundred percent at 20°C). The spinning draft is also independent of the properties of the drawn fibre.
