Preparation and performance of an immiscible PVC-HDPE blend compatibilized with maleic anhydride (MAH) via in-situ reactive extrusion

The mechanical and thermal properties of an uncompatibilized blend, i.e., polyvinyl chloride-high-density polyethylene (PVC-HDPE), can be improved by introducing maleic anhydride (MAH) into the blend polymer. The impact of this compatibilizer was investigated using Fourier Transform Infrared (FTIR) spectroscopy and density functional theory (DFT) calculations, which revealed that MAH forms bridges between the PVC and HDPE polymers. Scanning electron microscopy (SEM) showed the single-phase morphology of a (PVC-HDPE)-g-MAH blend, demonstrating improved adhesion between the two immiscible polymers. Further, thermogravimetric analysis (TGA) indicated that incorporating MAH increased the initial thermal degradation temperature (Tonset) of the blend at approximately 31 °C. Moreover, dynamical mechanical analysis (DMA) and differential scanning calorimetry (DSC) results showed a clear increase in the glass transition temperature (Tg) due to the incorporation of MAH in the polymer blend. This increase in the Tg value indicates that the addition of MAH into the PVC-HDPE blend enhances the thermodynamic compatibility of the blend. Finally, the addition of MAH increased the tensile modulus by more than 17%, improved the flexural modulus up to 25%, and increased the complex viscosity of the PVC-HDPE blend.