ABSTRACT
As a variation on the process outlined above, complete solvent removal may take place prior to hot drawing [36,49,54,55]. In this case the solvent, which is typically paraffin oil, is extracted with another organic solvent of lower molecular weight, such as methanol or hexane. Final drying to yield porous filaments is achieved under vacuum. The porous filaments may be hot drawn to yield ultrahigh modulus fibers. Dried porous filaments cannot be drawn to the same extent as wet gel filaments produced under identical spinning conditions. However, at a given draw ratio the tensile modulus of the fibers is identical irrespective of whether they were dried prior to hot drawing.
