Evaporative cooling mixed feed

If the crystallizer is not of the evaporative type but rehes only on adiabatic evaporative cooling to achieve the yield, the heating element is omitted. The feed is admitted into the circulating hue after withdrawal of the slurry, at a point sufficiently below the free-hquid surface to prevent flashing during the mixing process. 

The polymer is dissolved in 100 ml of methanol and mixed with a solution of 15 g of NaOH in 100 ml of methanol. In a round bottom flask equipped with a feed pipe and a reflux condenser, the mixture is boiled under nitrogen for a period of 2 hours. Then the methanol is distilled off as far as foam formation will permit. After addition of 200 ml of toluene, the mixture is distilled under a weak vacuum until the distillation temperature becomes constant. After cooling and addition of another 200 ml of toluene, the mixture is extracted with 100 ml quantities of water in a separating fiinnel until the aqueous phase is neutral. The toluene phase is dried with anhydrous sodium sulfate and clarified before the toluene is removed in a rotary evaporator. The remaining viscous liquid is an almost colorless PTMEG having a mean molecular weight between 800 and 1000. 

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