Mathematical modeling of melting of polymers in barrier-screw extruders

Some of today's modern screws contain melt-separating secondary (barrier) flights in the transition zone. With increasing utilization of barrier screws, the availability of proper and accurate design methods for the melting zone remains of paramount importance. A modified version of a mathematical model developed by the authors previously is applied to two most common types of barrier screws, viz. —The Mailefer screw (varying pitch and constant depth); —The Barr screw (constant pitch and varying depth). The present analysis provides valuable insight into the operating principles of these screws. A comparative study is presented demonstrating the possible advantages and disadvantages of the Maillefer and Barr screws in relation to conventional compression screws.