The Morphology of Crystalline Polymers P. H. Geil Polymer Group, Dept. Metallurgy 8 Mining Engineering, University of Illinois, Urbana, IL 61801 Polymer morphology involves characterization of the size, shape, and interaction of supermolecular structures, for example, of crystals in crystalline polymers, domains in block copolymers and regions of order, if any, in amorphous polymers. For any given resin, one whose configuration or chemical structure has been defined by the polymerization process, the physical properties are primarily dependent on the morphology which in turn is dependent on prior the'rmal and mechanical treatment, that is, on the processing history. Thus, in developing a polymer for a given end use one needs to understand and control the processing-morphology-property relationships. Current understanding of the morphology of crystalline polymers dates from 1957, the year in which the growth of single crystals of polyethylene was described and the concept of chain folding was proposed. Although considerable controversy over this concept has developed in the last several years, it is still believed, by this author, to be the appropriate "ideal" model to describe the property of crystalline polymers of reasonable degrees of crystallinity, for example, above 50%. The nature and effect of defects on the structure and properties is in need of continuing research. A summary of current understanding of the morphology of crystalline polymers (unoriented, that is, prior to deformation as occurs in the preparation of many fibers and films) suitable for use in the classroom has been published recently as an educational module in Journal of Educational Modules in Materials Science and Engineering (JEMMSE, Feh. 1981).
As described in another article in this issue (Geil, P: H., and Carr, S., J. CHEM.EDUC. (1981)) these modules c h he reproduced free of charge for classroom use and, thus, it is not reprinted here. The module considers (a) Recognition and measurement of crystallinity in polymers (h) Polymer single crystals (1) growth and thickness (2) concept of chain folding (3) thermal properties (4) theorv of lamellar ervstallization
(1) single crystals and axialites (2) (3) (4) (5) (6)
spherulite morphology impurity segregation model of growth temperature and pressure effects crystallization from oriented melts property-morphology relationships
With respect to properties, primary consideration is directed toward understanding prr~vsiing-morpholo~.~~ropert). relatio~nhipifor 2 propertirs, modulus or stiffness and small mdrrllle !gas1 diffusion. 11 i i assumed the student ir familiar with the long chain nature of polymers, with the module being suitable both for introductory polymer science courses and polymer section of materials science courses. It is designed to be covered in 2-3 lectures hut can he used as supplemental reading for a one-hour lecture.
Volume 58
Number 11 November 1981
879
