The aliphatic polyester poly(butylene succinate) (PBS) and its random copolymers poly(butylene succinate-co-adipate) (PBSA) are among the most attractive commercially available biopolymers to compete with petrobased polyolefins in a wide range of soft and flexible thermoplastic applications such as blown and flat films, thermoforming, blow molding and injection molding. Due to its high relevance of PBSA as mono material or as blend component in flexible film applications, a sound understanding of compounding, further processing and film properties is necessary. 

In this work, PBSA, poly (lactid acid) (PLA) and blends at three different compositions thereof were processed to flat and blown films. Investigating the films with X-ray diffraction (XRD), multivariate confocal Raman microscopy (CRM) and scanning electron microscopy (SEM) revealed the semicrystalline order as well as the blend morphology. While PBSA is crystalline, PLA remains amorphous after the processing step. As imaged with CRM the blend morphology of the flat films shows lamellar-like and oriented domains of the blend components due to the uniaxial stretching and quick cooling to the solid state. We discuss these findings in light of the thermo-mechanical properties of the films and relevant implications for the processing.