Improvement of PBAT Processability and Mechanical Performance by Blending with Pine Resin Derivatives for Injection Moulding Rigid Packaging with Enhanced Hydrophobicity

Polybutylene adipate-co-terephthalate (PBAT) is a biodegradable polymer with good features for packaging applications. However, the mechanical performance and high prices of PBAT limit its current usage at the commercial level. To improve the properties and reduce the cost of PBAT, pine resin derivatives, gum rosin (GR) and pentaerythritol ester of GR (UT), were proposed as sustainable additives. For this purpose, PBAT was blended with 5, 10, and 15 wt.% of additives by melt-extrusion followed by injection moulding. The overall performance of the formulations was assessed by tensile test, microstructural, thermal, and dynamic mechanical thermal analysis. The results showed that although good miscibility of both resins with PBAT matrix was achieved, GR in 10 wt.% showed better interfacial adhesion with the PBAT matrix than UT. The thermal characterization suggested that GR and UT reduce PBAT melting enthalpy and enhance its thermal stability, improving PBAT processability. A 10 wt.% of GR significantly increased the tensile properties of PBAT, while a 15 wt.% of UT maintained PBAT tensile performance. The obtained materials showed higher hydrophobicity than neat PBAT. Thus, GR and UT demonstrated that they are advantageous additives for PBAT–resin compounding for rigid food packaging which are easy to process and adequate for industrial scalability. At the same time, they enhance its mechanical and hydrophobic performance.