Reactive extrusion of sustainable PHBV/PBAT-based nanocomposite films with organically modified nanoclay for packaging applications: Compression moulding vs. cast film extrusion

Abstract

The mechanical, thermal and barrier properties of a sustainable PHBV/PBAT blend was investigated under the influence of organically modified nanoclay (0.6, 1.2 and 1.8 wt%) after processing by two different techniques i.e. compression moulding and cast film extrusion. Firstly, a pelletized nanoclay masterbatch was fabricated by blending PBAT with 20% nanoclay using melt extrusion. The masterbatch was used as a reinforcement phase for the PHBV/PBAT blend matrix to fabricate nanocomposite pellets using a melt extrusion process. The prepared PHBV/PBAT/Nanoclay nanocomposite pellets were used to fabricate films using compression moulding and cast film extrusion. The cast extruded PHBV/PBAT nanocomposite films showed improved barrier properties (oxygen and water vapour) as compared to compression moulded films because of the chain orientation during the high-speed stretching. The barrier properties results showed significant improvement of ~79 and ~70% in oxygen and water vapour permeability respectively in cast PHBV/PBAT composite films after adding 1.2 wt% nanoclay, which indicates a good dispersion of nanoclay and strong interfacial adhesion between the matrix and filler. The intercalation/exfoliation of nanoclay in PHBV, as well as at the interface of the PHBV and PBAT blend matrix, was confirmed by transmission electron microscopy (TEM). The % elongation at break (567.6 ± 0.1) of the cast PHBV/PBAT/Nanoclay(1.2%) nanocomposite film was highly improved as compared to that of the PHBV/PBAT blend due to better stress transfer ability as compared to the compression moulded film. The rheological properties also support better dispersion of nanoclay and interaction between the matrix and filler. Hence, the cast extruded nanocomposite film with 1.2% nanoclay is a potential candidate to be used in flexible packaging.