Modification of PLA for improved layer-to-layer adhesion in 3-D printed parts

This study examines the influence that modifying the chemical structure of poly(lactic acid) can have on improving the mechanical properties of a 3-D printed part. A multi-functional chain extender was used to change the polyester such that its rheological response resembled an increasingly branched polymer chain. The modified polyesters were printed into two-layer rectangular specimens and subsequently analyzed for tensile properties as well as adhesive strength by 180^o peel testing. With increasing chain extender content, the printed specimen exhibited increased toughness and tensile strength, along with greater adhesive strength. The more highly branched, the greater interlayer adhesion as polymer chains diffusion and entangle across the interface.