ABSTRACT
The key to understanding why S3P is fundamentally different in the way it affects the in-process material lies in the fact that it causes individual solid pieces to fracture, while simultaneously causing "cold welding" of others. Mechanistic details of these processes are covered in Chapter 3 of this book. The mechanochemistry that occurs is the heart of what happens during S3P processing. Chain scission occurs during these particle cleavage events that are associated with the size-reduction process. There then follows a cascade of subsequent chemical events, including the formation oflower molecular weight species, hetero-block and graft species, and stereoregular chains with racimized segments. Macromolecules involving chains from two different polymers are formed as a result of"cold welding" between two particles of dissimilar composition. Such "cold welding" happens when high-shear stresses in the presence of high hydrostatic stress fields urge chains together with sufficient energy to cause exchange of chemical bonds to occur.
