Effect of PET functionalization in composites of rubber-PET-HDPE type

The functionalization of polyethylene terephthalate (PET) from tire rubber-PET-high density polyethylene (HDPE) composites represents a key strategy for improving the composite properties. This is a practical and effective method to improve the interface between matrix (waste tire rubber) and fillers (waste PET and HDPE). By PET functionalization, adherence and surface properties of composite materials can be controlled. PET functionalization was performed with polyethylene glycol (PEG 400, 1%) and sodium dodecyl sulphate (SDS 1%). The characterization of the components and composite are discussed in terms of surface energy values (evaluated from water contact angle measurements) and surface morphology by using scanning electron microscopy (SEM). The structural and conformational changes were investigated by Fourier Transform Infrared (FTIR) Spectroscopy while the crystalline structure was studied by X-ray diffraction (XRD). The improved interfacial adhesion, thermal stability and mechanical properties (stress-strain, compression and impact resistance) of the composites are correlated with the PET functionalization, with non-ionic (PEG) and an anionic surfactant (SDS). The results proved that the interface properties are improved by functionalization of PET. The best mechanical properties were recorded at 30 min moulding. The samples with 45% PET-SDS showed the best combination of mechanical properties: tensile strength (1.56 N/mm2), impact strength (43.72 kJ/m2) and compression (158.78 N/mm2).