Novel Bio-based Immiscible Blends of Poly(Butylene Succinate)/Poly(Ethylene Brassylate): Effect of PEB Loading on Their Rheological, Morphological, Thermal and Mechanical Properties

Poly(butylene succinate) (PBS)/poly(ethylene brassylate) (PEB) biodegradable polyester blends were prepared at different PEB contents (5 to 30 wt%) to study the influence of the addition of PEB on the rheological behavior, morphology, thermal and mechanical properties of the blends. A gradual decrease in the shear viscosities and a greater shear thinning behavior were observed with increasing PEB content due to its low molecular weight, which acted as a lubricant or plasticizer, favoring the disentanglement of PBS chains. The blends with higher PEB content (25 and 30 wt%) had higher activation energy values and were more sensitive to temperature variations. The morphology showed good dispersion of PEB in the PBS matrix. Still, increased PEB content led to larger droplets, indicating immiscibility and poor adhesion between phases. PEB influenced both nucleation density and spherulite size of PBS/PEB blends, denoted by an increasing degree of crystallinity, a shift to low crystallization temperatures, and an improvement in the decomposition temperature according to their thermal properties. Low PEB contents (5 and 10%) increased PBS toughness due to the higher crystalline fraction and smaller crystal size of these blends.