Properties of Blends from Polypropylene and Recycled Polyethylene Terephthalate using a Compatibilizer

Abstract

Polyethylene Terephthalate (PET) is a major constituent of the plastic waste generated on a day-to-day basis. Replacing a proportion of the virgin Polypropylene (PP) with recycled Polyethylene Terephthalate (r-PET) through polymer blending is cost-effective and sustainable method to increase the mechanical characteristics of PP. A compatibilizer namely Polypropylene grafted maleic anhydride (PP-g-MAH) is utilized to reduce immiscibility between them through chemical reactions involving the maleic anhydride group. In this study, PP/r-PET blend ratio is maintained at 80/20. The polymer blends prepared by twin screw extrusion are converted to test specimens by injection moulding. The mechanical and thermal properties of the blends are studied by performing characterization techniques like Tensile Tests and Differential Scanning Calorimetry (DSC). Fourier Transform Infrared Spectroscopy (FTIR) analysis shows the reaction occurring at the interface during compatibilization. Scanning Electron Microscopy (SEM) suggests the significance of compatibilizer in the microstructure development of the blend for the effective dispersion of the r-PET in PP. The crystallization temperature of PP is moved to higher temperatures in the presence of both the r-PET and the compatibilizer as evident from the DSC analysis. The addition of the compatibilizer improved the tensile strength, elongation at break and the modulus of elasticity of the blend. The blend containing 4% PP-g-MAH exhibited the optimum set of properties.