be arranged in a rectangular geometry these rectangles being substantially parallel to each other and extending longitudinally again keeping the spacing larger at the viscous end and smaller at the less viscous end the agitator may be thus built in sections that appear like a 34 stack 34 or a 34 sandwhich 34 of rectangular assemblies these sections may be installed in the agitator frame staggered e g the plane of one section may be perpendicular to those of the next section to as to keep the inert gas well distributed and to minimize by passing running through of the melt by making the path more tortuous in fig4 the elements are meshed screens but these could be of other configurations such as rods or punched sheets of metal in this type of agitator the melt picked up by the wipers during their travel through the pool at the bottom and thereafter shed by the wipers flows along the rectangular elements to generate surface area the agitator is rotated at a rate rpm that maximizes the generation of surface area and provides frequent surface renewal faster surface renewal is advantageous for increasing the coefficient of transfer of volatile products from the reaction melt to inert gas but rotation that is too fast can result in the viscous polymer melt being held as 34 globs 34 between the elements and in fact decrease the surface renewal rate for.