Effect of modification extent of montmorillonite on the performance of starch nanocomposite films

Abstract

The mechanism of the influence of organically modified montmorillonites (OMts) with different modification extents on starch/OMt nanocomposites was investigated. The nanostructures of OMts and their dispersion in starch films were analyzed using X‐ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The modifier content in the OMts increased with an increase in the added amount and molecular weight of the modifiers. The highest d‐spacing of 3.71 nm was achieved for the OMt modified with 30% dioctadecyl dimethyl ammonium chloride (DDAC). Intercalated nanostructures were formed between starch and the OMts modified with DDAC, whereas exfoliated nanostructures were formed between starch and the OMts modified with octadecyltrimethyl ammonium chloride (OAC) and octadecyl dimethyl benzyl ammonium chloride (ODBAC). The films with the OMt modified with 50% DDAC exhibited the highest tensile strength of 6.22 MPa. The water vapor permeability (WVP) of the film with the OMt modified with 30% DDAC exhibited a minimum value of 1.63 × 10−10 g · m/m2 · s · Pa. The amount and types of the modifiers in the OMts significantly influenced the structure and properties of the starch/clay nanocomposites. For a given polymer, the modification extent of Mt should be optimized to achieve high‐performance nanocomposites.