Statistical optimization of compatibilized blends of poly(lactic acid) and acrylonitrile butadiene styrene

A mixture design of experiment and subsequent regression analysis was used to study the effects of two additives on blends of poly(lactic acid) (PLA) and acrylonitrile butadiene styrene (ABS). Statistical analysis was used to find a blend with a balance of high toughness, strength, and stiffness. The blends were prepared by lab scale reactive extrusion and injection molding. Least‐square regression models of statistically significant effects were built by analysis of variance (ANOVA). Using these models, optimization studies were used to study the predicted maximum values of each measurement criteria. Very large increases were seen in the measured responses with relatively small changes in additive content. Compared to the neat blend without additives, the impact strength was increased by over 600%, the elongation at break was increased by over 1000%, the tensile strength increased by 11%, and the tensile modulus increased by over 7%. Surprisingly, the composite optimization, which included all measured criteria, occurred at a point that allowed all four criteria values to remain very close to their individual maximums. The result is a partially biobased blend that does not sacrifice strength or stiffness to achieve very high toughness.