Acid temperature control advantages

In this process, the oil is firstly hydrolyzed to give free fatty acids which are then heated at 200-240°C with a mixture of polyol and dibasic acid. Simultaneous condensation of the polyol, dibasic acid and fatty acids thereby occurs and the latter become incorporated into the polymer structure. The process may be conducted in two ways. In the first procedure, which is known as the fusion or solventless method, the reactants are heated in a simple kettle under an inert atmosphere. At the end of the heating period, inert gas is blown into the resin to remove water and unreacted materials. In the second procedure, which is known as the solvent or solution method, a small amount (generally about 5%) of a solvent, usually xylene, is added to the reactants. The mixture is heated in a reactor fitted with equipment which condenses volatile vapours, separates water and returns the organic distillate to the reactor. The solvent facilitates removal of water by azeotropic distillation and, compared to the fusion method, allows much better temperature control. In addition, the solvent reduces the viscosity of the reactants this permits more effective agitation which contributes to easier water removal and faster reaction. The solvent also continually cleans resin from the sides of the reactor and enables a more uniform product to be prepared that is free from gel particles. However, despite these advantages of the solvent method over the fusion method, the latter is widely used since it requires simpler equipment. 

The unique advantage of the plasma chemical method is the ability to collect the condensate, which can be used for raw material decomposition or even liquid-liquid extraction processes. The condensate consists of a hydrofluoric acid solution, the concentration of which can be adjusted by controlling the heat exchanger temperature according to a binary diagram of the HF - H20 system [534]. For instance, at a temperature of 80-100°C, the condensate composition corresponds to a 30-33% wt. HF solution. 

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