Effects of preparation methods on the structure and mechanical properties of wet conditioned starch/montmorillonite nanocomposite films

•Intercalated structure and VH-type crystallinity of starch were found.•Clay reinforces TPS considerably due to strong starch/clay interactions.•Reinforcing effect of clay depends on the plasticizer content of TPS.•Preparation method influences the mechanical properties of wet conditioned samples. TPS/Na–montmorillonite nanocomposite films were prepared by solution and melt blending. Clay content changed between 0 and 25wt% based on the amount of dry starch. Structure, tensile properties, and water content of wet conditioned films were determined as a function of clay content. Intercalated structure and VH-type crystallinity of starch were found for all the nanocomposites independently of clay and plasticizer content or preparation method, but at larger than 10wt% clay content nanocomposites prepared by melt intercalation contained aggregated particles as well. In spite of the incomplete exfoliation clay reinforces TPS considerably. Preparation method has a strong influence on mechanical properties of wet conditioned films. Mechanical properties of the conditioned samples prepared by solution homogenization are much better than those of nanocomposites prepared by melt blending. Water, which was either adsorbed or bonded in the composites in conditioning or solution mixing process, respectively, has different effect on mechanical properties.