ABSTRACT
This chapter deals with the density of polymeric materials and the surface characterization of solid polymers. The density of a polymer sample is a sensitive probe of the organization of polymer chains within the solid. Large variations in density can be found in non-crystalline polymers as a consequence of differences in their thermo-mechanical history. The signal for a torsional vibration is relatively much larger for neutron diffraction and this can help to identify the source of the various relaxations obtained from a polymer. Polymethyl methacrylate adopt a conformation which is either present polar or nonpolar groups at the surface and samples have been observed to change their surface properties with time depending upon which state represents the lower surface energy. The chapter describes two approaches to the analysis of polymer surfaces, both based on vacuum methods of analysis and hence limited to stable polymer surfaces: electron spectroscopy for chemical analysis and secondary ion mass spectroscopy.
