Direct Compounding Injection Molding and Resulting Properties of Ternary Blends of Polylactide, Polybutylene Succinate and Hydrogenated Styrene Farnesene Block Copolymers

Direct compounding injection molding of ternary blends of polylactide (PLA), polybutylene succinate (PBS) and a hydrogenated styrene farnesene block copolymer (HSFC) was investigated for different blend compositions. Morphological analysis by atomic force microscopy and scanning electron microscopy showed a heterogeneous morphology of the ternary blends, with coexisting droplets of HSFC and PLA respectively PBS. Particle sizes analysis of the minor phases in the ternary blends showed mean values in the range of ∼1 mm, which is discussed in correlation to the rheological properties of the blend components as obtained by high pressure capillary rheometry. In result, with increasing HSFC content, the ternary blends showed a significant increase in notched Charpy impact strength (acN). In concrete, for the ternary blends with 15 wt% of HSFC a maximum acN of 15.8 kJ/m2 was found. At the same time, incorporation of the HSFC resulted only in a moderate reduction in elastic modulus and tensile strength.