Effect of Uniaxial Drawing on Gas Transport Properties of Poly(Butylene Succinate) Based Films: Structure‐Properties Relation

ABSTRACT In this work, two PBS poly(butylene succinate) films composed on one hand of neat PBS and on the other hand of PBS containing 1 wt% of silica are uniaxially stretched at 85°C up to a draw ratio (DR) of 6. The influence of stretching on the chain mobility and on the crystallinity is investigated by differential scanning calorimetry (DSC). WAXD analysis shows that the stretching process induces a preferential orientation in the crystalline phase with the alignment of the c‐axis of the crystal lattice in the drawing direction. As evidenced by SAXS analysis, upon stretching, a complex microstructure is created involving a two‐scale texturing: at a small scale in the stretching direction and at a larger scale in the transverse direction. Based on DSC and SAXS results, the development of this microstructure is assigned to a fibrillation phenomenon. Gas permeability does not vary monotonically as a function of DR: it increases for DR values up to 3 and then decreases. This unusual behavior is discussed as a function of the respective evolution of the polymer structure, crystallinity and chain mobility, the effect of the silica filler being mostly observed for DR up to 3.