Effective Young’s modulus of biopolymer composites with imperfect interface

The effective elastic behaviour of a biopolymer composite with random microstructure is studied. The effective elasticity modulus is computed as function of the protein fraction with the hypothesis of an imperfect interface. This interface is handled considering normal and tangential stiffness parameters. The methodology assumes the direct import of real microstructures of starch–protein (zein) composite, obtained using Confocal Laser Scanning Microscopy (CLSM), into a finite element model. A static linear analysis is conducted to determine the influence of interface rigidities, zein fraction and interface quantity on the effective properties. Predictions show that the effective modulus is nonlinearly correlated to the product of stiffness parameters for which the normal stiffness is the most influential parameter. The effective property dependence with respect to interface related variables and zein fraction shows a logarithmic influence of the stiffness parameters when increasing zein fraction.