Abstract: Polymeric blends and filaments prepared from the blends are provided for improving isotropy in three-dimensional objects prepared by fused deposition modeling (FDM) processes. The polymeric blends include a high molecular weight (HMW) thermoplastic polymer and an additive comprising a low molecular weight (LMW) thermoplastic polymer. The HMW and LMW polymers can be the same type of polymer (e.g., poly(lactic acid)) or have at least one type of monomeric unit in common. The LMW polymer additive can have a molecular weight that is greater than the entanglement molecular weight and is about half the molecular weight of the HMW polymer or less. Inclusion of the LMW polymer can increase interfacial adhesion between filaments prepared from the blends. Also provided are three-dimensional objects prepared from a FDM process that have improved isotropic properties and methods of improving the isotropic properties of a three-dimensional object.