Polypropylene/polypropylene-grafted acrylic acid copolymer/ethylene-acrylic acid copolymer ternary blends for hydrophilic polypropylene

Ternary blends of polypropylene (PP), a polypropylene-grafted acrylic acid copolymer (PP-g-AA), and an ethylene-acrylic acid copolymer (EAA) were prepared by melt blending. The surfaces of films with different contents of these three components were characterized with contact-angle measurements. Scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the microstructure, melting and crystalline behavior, and thermal stability of the blends. The contact angles of the PP/PP-g-AA blends decreased monotonically with increasing PP-g-AA content. With the incorporation of EAA, the contact angles of the PP/PP-g-AA/EAA ternary blends decreased with increasing EAA content. When the concentration of EAA was higher than 15 wt %, the contact angles of the ternary blends began to increase. Scanning electron microscopy observations confirmed that PP-g-AA acted as a compatibilizer and improved the compatibility between PP and EAA in the ternary blends. Differential scanning calorimetry analysis suggested that acrylic acid moieties could act as nucleating agents for PP in the polymer blends. Thermogravimetric analysis and differential thermo-gravimetry confirmed the optimal blend ratio for the PP/ PP-g-AA/EAA ternary blends was 70/15/15.