Cooling in melt

Evaporation of solvent is a relatively slow process, slower than cooling in melt spinning. It is therefore essential that the spinning filaments are thin. The common approach is to use small spinning holes (50-100 gm) and apply a low draft in the spin-line. For example, both the extrusion speed from the holes and the exit speed from the dry-spinning column would be around 300 m min . Even a draft below 1 is possible, which means that the die swell effect is not completely undone. 

Saponify 5 g of the oil with ethanolic potassium hydroxide, evaporate the ethanol, make up to 100 ml and liberate the fatty acids. Cool, extract twice with ether and make the ether extracts up to 100 ml. Pipette 20 ml into a 50-ml flask, add 2 ml of glacial acetic acid and cool in melted ice. Add bromine, drop by drop, from a burette until a permanent brownish-red colour results. Stopper the flask and leave at 0° for at least four hours. Decant the liquid, wash the precipitate three times in the flask with 5 ml of cooled ether, transfer the crystals to a weighed filter, using two more portions of 5 ml of cooled ether for transferring and washing. Dry to constant weight at 100 and determine the melting-point. 

With very low flashing oils, the sample (sometimes the oil cup ilsell) may be cooled in melting ice before filling. 

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