Characterisation of the matrix polymer morphology of polyolefins foams by Raman spectroscopy

The spatial resolution provided by micro-Raman spectroscopy is used to probe the morphology of the polymer matrix in a series of closed cell cross-linked polyolefin foams. The experiment set-up allows for the laser beam to be focused with a spatial resolution of 1 μm2, permitting the structural characterisation of the polymer in the cell faces, cell edges and vertices; i.e. the main constituents which build up the cellular structure of a closed cell foam. The spectra of the solid sheets utilised to produce the foams are used as reference in the discussion of the results for foams. The results have showed a non-homogeneous spatial distribution of the polymer morphology in the foam, which is different from the morphology of the solid sheets. Orientation and phases content are the main sources for these differences.