ABSTRACT
Chain-growth homopolymerizations are generally single-component reactions that occur throughout the bulk of the material as only one component or an ideal mixture of two or more components is present. The growth of a chain is usually initiated by an initiator. The chain grows in a very short period of time to its final length after which it terminates by combination with another chain or by disproportionation. The initiator types used in chain-growth polymerizations are radical formers, carboanionics, carbocationics, or complex-forming agents. Most reactive extrusion processes are initiated by radical formation, for instance, with peroxides. In reactive extrusion the temperature is affected by the wall temperature and the heat transfer coeffcient but also by the reaction velocity, which, in turn, is influenced by the radical concentration and the temperature. Chain transfer is a process in which a growing polymer chain with a free radical removes an atom from a molecule, resulting in an inactive polymer molecule and a new radical.
