Correlation of morphology, rheology, thermal, and mechanical properties in PP/EOC blends in presence of nanoclay and compatibilizer

To expand the range of applications and overcome mechanical limitations of Polypropylene (PP), a commonly used industrial polymer, toughness modification is required. In this study, PP was toughened with ethylene octene copolymer (EOC) and nanoclay platelets and the blends and nanocomposites of PP/EOC were prepared by means of a melt mixing process, and the effect of different grades of EOC, the addition of nanoclay platelets, and the effect of compatibilizer on properties of the final system were investigated. Scanning and transition electron microscopy, X-ray diffraction, rheology, differential scanning calorimetry, and dynamic-mechanical analysis were conducted to correlate the structure to the resulting properties. The results indicate that different grades of EOC with different molecular weights and viscosity can have a tremendous impact on droplet size and final properties of the blend sample. From a morphological point of view, the addition of EOC grade with higher viscosity (n(i)) in PP/EOC blends results in droplet matrix structure with larger EOC droplets. To decrease the droplet size, and hence improvement in final properties, nanoclay and compatibilizer were introduced to the blend. According to the results, selective localization of nanoclay and proper dispersion degree of nanoclay in the PP/EOC blend with higher viscosity grade of EOC containing nanoclay up to 3 wt.% lead to amelioration of the final properties of the system including complex viscosity, storage modulus, damping, and crystallinity. Moreover, the addition of the compatibilizer to the nanocomposite samples with 5 wt.% nanoclay can compensate for the deteriorated properties which occurred as a result of nanoclay aggregation in this system. This indicates that the addition of the nanoclay and compatibilizer plays an important role in toughening, morphology, and determining the final properties of the system as well.