Preparation and properties of polypropylene-asphaltene composites

In this study, novel composite materials of polypropylene (PP) with asphaltenes taken from Arab heavy atmospheric residue were prepared and characterized. Composites with various relative amounts of asphaltenes to PP were formed using the melt-mixing technique. The chemical structure, crystalline form, and morphology of these materials were examined using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) measurements. Their thermal properties were measured with differential scanning calorimetry (DSC), their thermal degradation characteristics with thermogravimetric analysis (TGA), and the mechanical properties using an Instron dynamometer. It was found that the crystalline and chemical structure of PP is not affected by the presence of asphaltenes, whereas the thermal stability, crystallinity, and tensile mechanical properties are enhanced with the amount of asphaltenes. Particularly, the addition of 5 wt% asphaltenes could improve tensile strength and the Elastic modulus by almost 10%. Better dispersion is achieved at relative low percentages of asphaltenes. It was found that the optimum amount of asphaltenes to result in composites with good dispersion, enhanced thermal stability, tensile strength, and relative crystallinity was 5 wt%. Most of these properties seem to deteriorate when the amount of asphaltenes added is high (i.e., 10%–15%). Therefore, a new use of a by-product of the petroleum refinery industry is proposed resulting in improved properties of a commodity polymer. POLYM. COMPOS., 38:1957–1963, 2017.