Parts prepared by the fused deposition modeling (FDM) 3D printing process suffer from poor interfacial adhesion between layers. This is due to poor diffusion of the very large and slow polymer chains across the inter-filament interface. To address this issue, we have developed the use of a bimodal blend of poly(lactide) (PLA) comprised of a series of synthesized low molecular weight PLA components (8.5 k, 50 k, and 100 k) added to a commercially available PLA (220 k). Tensile testing results indicate that when the LMW additive is of a sufficient length, the maximum stress and modulus in the part printed orthogonal to the print head (transverse) is significantly improved. More specifically, this behavior is observed where increased diffusion and increased entanglement of chains across adjacent layers occurs. The extent of crystallization at various stages of processing is also analyzed and indicates no correlation between the mechanical properties obtained and extent of crystallinity. (C) 2017 Elsevier Ltd. All rights reserved.