P. S. HOPE and M. J. FOLKES Mixing two or more polymers together to produce blends or alloys is a well-established strategy for achieving a specified portfolio of physical proper ties, without the need to synthesise specialised polymer systems. The subject is vast and has been the focus of much work, both theoretical and experimental. Much ofthe earlier work in this field was necessarily empirical and many ofthe blends produced were of academic rather than commercial interest. The manner in which two (or more) polymers are compounded together is of vital importance in controlling the properties of blends. Moreover, particular ly through detailed rheological studies, it is becoming apparent that process ing can provide a wide range of blend microstructures. In an extreme, this is exemplified by the in situ formation of fibres resulting from the imposition of predetermined flow fields on blends, when in the solution or melt state. The microstructures produced in this case transform the blend into a true fibre composite; this parallels earlier work on the deformation of metal alloys. This type of processing-structure-property correlation opens up many new possi bilities for innovative applications; for example, the production of stiff fibre composites and blends having anisotropic transport properties, such as novel membranes. This book serves a dual purpose."

Block copolymers represent an important class of multi-phase material, which have received very widespread attention, particularly since their successful commercial development in the mid-1960s. Much of the interest in these polymers has arisen because of their rather remarkable micro phase morphology and, hence, they have been the subject of extensive microstructural examination. In many respects, the quest for a comprehensive interpretation of their structure, both theoretically and experimentally, has not been generally matched by a corresponding enthusiasm for developing structure/property relationships in the context of their commercial application. Indeed, it has been left largely to the industrial companies involved in the development and utilization of these materials to fulfil this latter role. While it is generally disappointing that a much greater synergism does not exist between science and technology, it is especially sad in the case of block copolymers. Thus these materials offer an almost unique opportunity for the application of fundamental structural and property data to the interpretation of the properties of generally processed artefacts. Accordingly, in this book, the editor has drawn together an eminent group of research workers, with the specific intention of highlighting some of those aspects of the science and technology of block copolymers that are potentially important if further advances are to be made either in material formulation or utilization. For example, special consideration is given to the relationship between the flow properties of block copo lymers and their microstructure."

P. S. HOPE and M. J. FOLKES Mixing two or more polymers together to produce blends or alloys is a well-established strategy for achieving a specified portfolio of physical proper ties, without the need to synthesise specialised polymer systems. The subject is vast and has been the focus of much work, both theoretical and experimental. Much ofthe earlier work in this field was necessarily empirical and many ofthe blends produced were of academic rather than commercial interest. The manner in which two (or more) polymers are compounded together is of vital importance in controlling the properties of blends. Moreover, particular ly through detailed rheological studies, it is becoming apparent that process ing can provide a wide range of blend microstructures. In an extreme, this is exemplified by the in situ formation of fibres resulting from the imposition of predetermined flow fields on blends, when in the solution or melt state. The microstructures produced in this case transform the blend into a true fibre composite; this parallels earlier work on the deformation of metal alloys. This type of processing-structure-property correlation opens up many new possi bilities for innovative applications; for example, the production of stiff fibre composites and blends having anisotropic transport properties, such as novel membranes. This book serves a dual purpose."