(b) Solution Process Continuous solution processes have found wide commercial utilization, the main advantage over bulk methods being a lessening of the problems associated with the movement and heat transfer of viscous masses. However, the technique does require the added steps of solvent removal and recovery. Typically, a mixture of monomer, solvent (3-12% ethylbenzene) and initiator is fed into a train of three polymerization reactors, each with several heating zones. The reaction temperature is progressively increased, rising from 110-130'C in the first reactor to 150-170'C in the last. The polymer solution is then extruded as fine strands into a devolatilizing vessel. In this vessel, which is at a temperature of 225'C, removal of solvent and unreacted monomer takes place, being aided by the large surface area of the strands. The molten material is fed into an extruder, extruded as filament, cooled and chopped. It may be noted that this type of process is commonly regarded as a continuous bulk process since the amount of solvent used is so small.
This is the end of the preview.
access the rest of the document.