It was found that introduction of 5 wt. % of MMT into the PLA matrix significantly
improved barrier properties of the film, which was reflected by a decrease in the transmission
of water vapour by more than 40%, of oxygen by almost 40%, and of carbon dioxide
by up to more than 80%. A further decrease in the film permeability (by 10–27%) was
achieved by extrusion blow moulding, the less-permeable films being obtained at a blow
moulding ratio of 4. Such a reduction in the permeability was caused mainly by ordering of
the MMT platelets within the PLA matrix during the blow moulding process, which has
been proved by transmission electron microscopy (TEM). The obtained results confirm the
effectiveness of extrusion blow moulding as a technique for manufacturing nanocomposite
films containing PLA as a matrix, which exhibit favourably modified barrier properties.