Characterization of starch/poly(vinyl alcohol)/clay nanocomposite films prepared in twin-screw extruder for food packaging application

Abstract

Starch/poly(vinyl alcohol)/montmorillonite (MMT) nanocomposites were prepared in a twin-screw extruder for food packaging film application. In order to obtain a better compatibility between starch and silicate layers, MMT modification was performed using citric acid. X-ray diffraction (XRD) analysis was used to characterize the expanded microstructure of citric acid-modified MMT (CMMT). The effects of some compositional and operational factors including poly(vinyl alcohol) content, CMMT content, screw speed, and temperature profile in the extruder, on the tensile strength parameter of resulted films were investigated by using Taguchi experimental design. It was found that PVA content, CMMT percentage and screw speed were the most important factors, respectively, affecting the tensile strength property; while the temperature profile was insignificant factor, in the range of examined levels. The best levels of examined factors that could lead to the maximum tensile strength were obtained. The optimum sample was further characterized by XRD, transmission electron microscopy (TEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), water uptake, biodegradability, oxygen permeability, and overall migration test.