Mechanical, barrier and morphological properties of starch nanocrystals-reinforced pea starch films

• Waxy maize starch nanocrystals (SNCs)-reinforced pea starch (PS) films were prepared.
• The addition of SNCs increased the tensile strength of the PS/SNCs composite films.
• The water vapor barrier of composite films was improved by nanocrystals addition.
• When the SNCs content was 1–5%, the surface of films was smooth and compact.
• The composite films with appropriate SNCs became more thermostable.

To characterize the pea starch films reinforced with waxy maize starch nanocrystals, the mechanical, water vapor barrier and morphological properties of the composite films were investigated. The addition of starch nanocrystals increased the tensile strength of the composite films, and the value of tensile strength of the composite films was highest when starch nanocrystals content was 5% (w/w). The moisture content (%), water vapor permeability, and water-vapor transmission rate of the composite films significantly decreased as starch nanocrystals content increased. When their starch nanocrystals content was 1–5%, the starch nanocrystals dispersed homogeneously in the composite films, resulting in a relatively smooth and compact film surface and better thermal stability. However, when starch nanocrystals content was more than 7%, the starch nanocrystals began to aggregate, which resulted in the surface of the composite films developing a longitudinal fibrous structure.