|Abstract:||There is a growing interest in biopolymers due to their biodegradability, biocompatibility, and edibility. Biopolymer applications include food packaging, biomedical applications, and as structural materials. However, their mechanical properties are limiting. Current research is focused on modifying the physical and chemical properties of biopolymers for better performance and broader applications. The addition of nanofillers has been proposed as a way to modify mechanical properties of biopolymers. This work is focused on biopolymers as edible materials, therefore biopolymers and fillers must meet this requirement. In this study, microcrystalline cellulose (MCC), nanocrystalline cellulose (CNC), CaCO3 nanoparticles, hydrophilic nanoclay and hydrophobic nanoclay were separately added as fillers to the polymers, konjac glucomannan (KGM), hydroxypropyl methylcellulose (HPMC), and zein to investigate their effect on tensile properties of composite films. Tensile properties were measured by dynamic mechanical analysis (DMA) obtaining stress (σ), strain (γ), and Young’s modulus (E). Results revealed significant differences between neat polymers. Fillers, at 2% w/w, affected film properties depending on their size, shape, and surface chemistry. Good dispersibility and the extent of polymer-filler interactions controlled the effect of nanofillers on film properties. Nano-size, high aspect ratio, and hydrophilicity showed significant effects on tensile properties over micro-size, low aspect ratio, and hydrophobic fillers. Hydrophilic nanoclay and CNC interacted better with biopolymer matrices than hydrophobic nanoclay, MCC, or CaCO3. The load limit of CNC in KGM and HPMC to increase σ of neat polymers was 2% and 4%, respectively. Further addition resulted in γ and σ decrement. Load differences were attributed to differences in microstructure between KGM and HPMC. Addition of CNC up to 50% w/w resulted in a higher value of E, suggesting a volume fraction effect of nanocomposite components on films properties. The conclusions of this study were that the addition of nanofillers to biopolymers can lead to reinforced composites if there is good interaction between filler and matrix. Nanocomposite technology offers to broaden the application of biopolymers through the design of new materials with competitive mechanical, thermal, and barrier properties.