Investigation of structure/property relationships in particulate composites through the use of Raman spectroscopy

Raman spectroscopy has been used to characterise the structure of three very different particulate composite systems: aramid particles in nylon 6.6, cast iron (graphite particles in an iron matrix) and C60 or carbon nanotubes in an epoxy resin matrix. In addition, Raman spectroscopy has been used to follow the stress-induced tensile deformation of the particles within the composite matrices. It is shown that, for the different composite systems, certain Raman band positions move to lower wavenumber upon the application of a tensile strain and that the rate of this Raman band shift gives an indication of the level of reinforcement from the dispersed particulate phase. In each case stress transfer between the matrix and particles is observed but, in general, it is demonstrated that particulate reinforcement is not as efficient as fibre reinforcement.