Wet and dry-jet wet spinning of acrylic fibres

A comparison of the wet-spinning and dry-jet wetspinning
of acrylic fibres has been carried out using a
commercial acrylic polymer (Courtelle). redissolved in dimethyl formamide. The higher speeds possible in dry-jet wet-spinning have been related to the higher free velocity and the higher draw ratios possible. It is believed that the presence of the air-gap in dry-jet wet-spinning allows the removal of the dies well effects as well as other viscoelastic behaviour before coagulation and that this leads to fibres with superior mechanical properties, especially in improvements in extensibility.
Conditions are described which allow the production of high
tenacity acrylic fibres with tenacity up to 5.8 g/d tex.

In an attempt to produce fibres with better mechanical
properties under hot-wet conditions, copolymershave been prepared using bicyclo [2,2,1] hepta-2,5-diene as a comonomer. Fibres from such copolymers have low extensibilities and satisfactory fibres could be made only by incorporating, in addition to the bicyclo [2,2,1] hepta-2,5-diene monomer, itaconic acid and by dry-jet wet-spinning. In one such case a fibre was obtained with a slightly higher hot-wet modulus and a considerably
reduced hot-wet extensibility when compared with Courtelle
fibre