Virtual Reality: Real Ponderings

A process and apparatus for manufacturing polyolefin fibers from a composition of the said polyolefins dissolved in a diluent, by subjecting the composition to flow at a velocity above a critical value in a tube or bundle of tubes, the temperature of the composition being within the range of critical temperatures of the said composition over at least a portion of the length of the tube or bundle of tubes and separating the fibers from the liquid diluent. The critical temperature range is below the temperature of solution of the polyolefin in the molten state in a diluent and is more specifically the range of temperatures in which the polyolefin remains in dissolved condition when the solution mixture is maintained at rest but precipitates when the mixture is subjected to certain disturbances such as, for instance, shearing. This typically is between 70 DEG and 130 DEG C. The lower limits of the critical velocity and the critical temperature are determined by the appearance of undesired powder co-precipitating with the fibers.