In conventional polymer processing, a thermal gradient is something that has to be mixed out of the polymer prior to extrusion. In reactive processing, thermal gradients at any point in the extruder can give a variable rate reaction or even promote the wrong reaction. Our counter-rotating, non-intermeshing twin screw design provides excellent distributive mixing along the entire wtted length of the screws. The mixing is the result of a flow pattern that provides multiple reorientations of the melt. This pattern provides a low shear continuous homogenization of the melt that effectively minimizes the magnitude of thermal gradients.

In high viscosity fluids, the temperature of the fluid rises as shear is applied to the fluid.

Removing the heat through conductive cooling may be ineffective and will introduce thermal gradients in the poylmer. To overcome this problem, NFM/Welding Engineers applies direct inert fluid contact technology. This technology was developed for our proprietary emulsion finishing process in order to provide extensive cooling capability. This technique avoids thermal gradients that accompany any conductive cooling mechanism. Inert fluid rates in each stage of the process can be as high as five times the polymer throughtput rate without reducing polymer throughput rate. Precise temperature control is accomplished by regulating the stage pressure if the inert fluid is boiling and by regulating the flow rate and temperature of the inert fluid if it is not boiling.

Mass transfer in highly viscous fluids is often rate-limiting in a reaction. NFM/Welding Engineers has the experience to establish rapid intimate contact of the reactants, regardless of whether the mass trasnfer is between a melt and a liquid, a melt and a vapor, two melt streams, or a crumb and a liquid or vapor. Our devolatilization technology can be readily applied to polycondensation reactions or any melt vapor mass trasnfer operation. Our mixing processing technology promotes contact between co-continuous insoluable phases. The continuous reorientation mechanism provides excellent distributive mixing of multiple melt phases.

Insufficient residence time is a common cause for failure of reactive extrusion process development. A residence time limitation will make the throughput capacity insufficient to justify commercialization. Our non-intermeshing twin screw design allows us to operate at higher throughput or longer residence time than competitive designs.