Incorporation of LDPE with Casein for the Development of Packaging Materials with Optimized Properties

The objective of the present study was to develop innovative sustainable packaging materials with improved properties, using low density polyethylene (LDPE) blended with casein in various concentrations, the latter being extracted from expired milk. The films were prepared in situ through extrusion. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) experiments were carried out to justify the successful integration of casein within the blends and to study the possible interactions between LDPE and casein. Scanning electron microscopy (SEM) was used to examine the surface morphology of the films. Increase of casein content in the blends led to rougher surface morphology, but the structure remained dense. Dynamic mechanical analysis (DMA) measurements were conducted to examine the thermomechanical properties of the films. Tensile studies were also made to calculate the stress at break and the maximum strain at break. Water vapor transmission method (WVTR) was used to calculate the diffusion coefficient and oxygen transmission rate (OTR) measurements were performed to calculate oxygen permeability for examining the barrier properties of the prepared films. The overall properties of the composite materials have the potential to be used as alternatives toward conventional packaging membranes.