A further reduction in the transmission of water vapour,
oxygen and carbon dioxide (by 10–27%) may be achieved
due to extrusion blow moulding of the nanocomposite PLA
film. The largest decrease in the transmission of these
substances occurs when the blow moulding ratio is 4. This
reduction in permeability is caused mainly by a more
parallel ordering of the MMT platelets within the PLA
matrix, induced by the film blowing. Thus, the diffusion
path of a substance elongates, which improves the barrier
properties of the blown films.