Optimising ductility of poly(lactic acid)/poly(butylene adipate-co-terephthalate) blends through co-continuous phase morphology

This paper examines the effect of the melt viscosities of the two component polymers on the morphology and mechanical properties of a series of biodegradable polymer blends. Melt blended compounds of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are prepared and their melt viscosities, thermal properties, crystallinity, mechanical properties and phase morphology are investigated. From the relative melt viscosities of PLA and PBAT in the processing regime used in the study, it is possible to calculate the volume fraction at which a co-continuous phase structure is formed. The predicted value is 19 wt% of PBAT and this value is verified by the results of mechanical properties, where results for elongation-to-break show a dramatic rise from around 10% up to 300% in the composition range between 10 and 20 wt% of PBAT. The co-continuous phase structure is also validated by scanning electron microscopy. Graphical Abstract: [Figure not available: see fulltext.]