Investigation on PLA/PHBHHx Blends: Morphological, Thermal and Mechanical Characterization

The paper focuses on developing novel biodegradable polymer blends, aiming to modulate their functional properties and increase their competitiveness for widespread applications. The main objective was to investigate the morphology and the properties of blends of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) prepared by melt compounding at various blend compositions: 0/100, 25/75, 50/50, 75/25 and 100/0 (w/w), respectively. The structure-properties relationships of PLA/PHBHHx blends were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis ( TGA), differential scanning calorimetry (DSC), and tensile measurements. The study showed that despite PLA and PHBHHx being two immiscible polymers, the FTIR data indicated, however, the occurrence of some chemical interactions between the blend components through transesterifications. SEM analysis showed a finer morphology, particularly for PLA/PHBHHx blend: 75/25, where the PHBHHx nodules having almost 200-300 nm size were embedded and homogeneously dispersed in the PLA matrix. Moreover, elongation at break improved significantly, leading to a good stiffness-toughness balance.