| Twin screw extruders in the modern plastic industry possess greater effectiveness over the single screw extruder in applications such as pumping, compounding, blending, devolatilization, reactive processing and profile extrusion. Most of these machines now have modular design, allowing for greater flexibility.; Recently, the authors and their co-workers have given attention to comparative studies of the mixing characteristics of different continuous mixers. In this dissertation, first we described an extensive comparative experimental investigation of the caprolactam polymerization in a batch mixer and various twin screw extruders. We also computed the development of interfacial area along the screw axis in those twin screw extruders as the index of distributive mixing.; Mixing has been the focal point of many experimental studies in recent years, but advances in modeling and simulation now allow fast, accurate and useful simulation analysis. Numerous mixing indices have been developed but the majority are tailored to experimental studies. It is the second purpose of this dissertation to make a serious effort at modeling reactive extrusion process. A new mixing index, coefficient of interfacial area growth, was developed to quantitatively analyze distributive mixing of composite modular twin screw machines and further to predict the polymerization behavior of caprolactam in various twin screw extruders. Our approach is to compute the development of interfacial area for composite modular twin screw extruders and an internal mixer, and the mixing index was determined for each processing device.; Living anionic polymerization of lactams allows the ready formation of multiblock copolymers with polyamide endblocks. This includes macromolecules with soft flexible inner segments, which might act as thermoplastic elastomers. Polyamide thermoplastic elastomers at the present form the high cost and performance end of commercial thermoplastic elastomers and the potential for new monomers would seem significant. The last three chapters address the reactive extrusion based synthesis of new segmented block copolymers, which include polyamide as hard segment and poly (tetramethylene ether glycol) (PTMEG), polycaprolactone and both as soft segments. These tri-/ or penta-block copolymers were synthesized in a modular intermeshing counter-rotating twin screw extruder. The block copolymers were also melt-spun-into oriented filaments from the die of a twin screw extruder, indicating the possibility of one step processing from monomer to product. |
