# From Film Processing to Microphase Orientation: Structure–Property Relationships in Commercial PBSA/PLA Blend Films

## TL;DR

This paper studies how processing affects the structure and properties of commercial PBSA/PLA blend films, revealing their mechanical and thermal behavior.

## Contribution

The study provides new insights into the microphase orientation and structure-property relationships in PBSA/PLA blends through advanced analytical techniques.

## Key findings

- PBSA is semicrystalline while PLA remains amorphous after processing.
- Flat films show lamellar-like domains due to uniaxial stretching and rapid cooling.
- Blown films lack preferential orientation and exhibit varied mechanical properties.

## Abstract

The commercialization of poly(butylene succinate-co-adipate) (PBSA), a biodegradable and potentially fully biobased random copolyester, is still ongoing. Due to its high relevance 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 (lactic acid) (PLA) and blends at three different compositions thereof were processed into flat films and blown films, respectively. 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 semicrystalline, PLA remains amorphous after the processing step. As imaged by CRM, flat films exhibit lamellar-like domains formed during uniaxial stretching and rapid cooling, whereas blown films show no pronounced preferential orientation. Tensile tests in both the machine and transverse directions demonstrate the versatility of PBSA and its blends in spanning a wide range of mechanical strength and flexibility, covering and partly exceeding the stiffness and strength ranges typically reported for commodity polyolefins while exhibiting reduced ductility. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) provide further insights into the thermal properties of the pure and blend materials.