Use of PP grafted with itaconic acid as a new compatibilizer for PP/clay nanocomposites

Abstract

Functionalized PP samples with different percentages of grafted IA, i.e., 0.7, 1 or 1.8 wt.-%, with similar molecular weights were used as compatibilizers in PP/clay nanocomposites. PP nanocomposites containing 1 wt.-% of organically modified clays, i.e., montmorillonite, natural hectorite and synthetic hectorite and 3 wt.-% of grafted PP with three different percentages of grafted IA as compatibilizers and two commercial PP samples of different molecular weights were prepared by melt blending. The nanocomposites were characterized by XRD, TEM and tensile mechanical measurements. It was found that the molecular weight of PP used as matrix as well as the percentage of grafted IA of the compatibilizer affected the degree of intercalation/exfoliation of the clay and consequently the mechanical properties of the nanocomposites. Values of 2137 MPa for the modulus and 51 MPa for the tensile strength were obtained when natural hectorite was used and 2117 and 40 MPa were obtained when montmorillonite was used. A comparative study was carried out, where PP grafted with maleic anhydride was used as the compatibilizer. Inferior mechanical properties were obtained for nanocomposites prepared by using this compatibilizer, where values of 1607 MPa for the tensile modulus and 43 MPa for tensile strength were obtained. This result indicated that IA-grafted PP was far more efficient as compatibilizer for the formation of nanocomposites than commercially available maleic anhydride-grafted PP.