Poly(Butylene Adipate-Co-Terephthalate)/Silane-Treated Wollastonite-Based Blown Film for Sustainable Packaging Application: Studying the Impact of Uniaxial Stretching on the Final Properties

The demand for biodegradable packaging is rising due to plastic pollution corncerns. This study develops biodegradable composites based on poly (butylene adipate-co-terephthalate) (PBAT) and silane-treated wollastonite (S-W) at two concentrations (15 and 25 wt%) through a combination of melt extrusion and blow-film extrusion techniques. Next, the PBAT/S-W composite films underwent uniaxial stretching in the machine direction (MD) to study the effects on their morphology, mechanical and thermal properties, barrier performance, contact angle, and X-ray diffraction (XRD) at different stretch ratios (SR). The incorporation of S-W at 15 wt% increased the mechanical properties, achieving ≈500% for tensile strength and 1000% for Young's modulus for SR6. Thermal and XRD analyses demonstrated that uniaxial stretching significantly enhanced film crystallinity because of strain-induced crystallization. Morphological analysis indicated two opposing effects at high SR: a pronounced alignment of molecular chains in the MD and weak adhesion between the filler and polymer matrix, which can impact the material's structural integrity. The water vapor barrier properties of the PBAT/S-W25% blown film at SR6 exhibited a remarkable 42% improvement compared to the unstretched version. This advancement, resulting from the elevated crystallinity, establishes PBAT/S-W as a viable eco-friendly substitute for single-use plastics in the field of biodegradable packaging.