Water Transport Properties of Poly(butylene succinate) and Poly[(butylene succinate)- co -(butylene adipate)] Nanocomposite Films: Influence of the Water-Assisted Extrusion Process

Poly(butylene succinate) (PBS) and poly-[(butylene succinate)-co-(butylene adipate)] (PBSA)-based composite films loaded with 5 wt % of fillers (native or organomodified montmorillonites) were extruded using a standard protocol or assisted by water injection. In the resulting composite films, the filler morphology was altered, as evidenced by TEM images. The CNa aggregates were broken with the help of water injection, and the exfoliation/dispersion levels of C30B were dependent on the matrix. By considering the degree of crystallinity of the polymer matrix, the nature of the fillers, and also the processing conditions, the film (micro)structure was successfully correlated to the water (liquid and vapor) behavior of the PBSand PBSA-based films, studied by means of sorption and permeation measurements. The water permeability and diffusivity were significantly reduced even with an increased water sorption, depending on the matrix and the clay morphology or nature. Specifically, concomitant effects such as tortuosity and trapping but also preferential diffusion pathways as well as free volumes in matrix strikingly were responsible for the barrier performances evolution.