The Interface mMorphology and Gas Barrier Property of PP and PET Blends were Improved by PP with Grafting Maleic Anhydride

To blend incompatible polymers, a third component, the compatibilizer, which improves the properties of the blend interface, is often used.

In this paper, polypropylene (PP) was grafted with maleic anhydride (PP-G-MAH) as compatibilizer to enhance the interfacial bond between polypropylene (PP) and polyethylene terephthalate (PET), and a film with high water vapor barrier was prepared.

Figure 1 is the SEM of 60%PET and 40%PP blend (1) and 60%PET, 37.5%PP and 2.5% PP-G-MAH blend (2).As can be seen from the figure, the blend without PP-G-MAH has obvious defects, which represent pores and granular PP phase, indicating poor compatibility between the two and low interface adhesion.With the addition of PP-G-MAH, copolymer dispersion is more uniform and defects are reduced, which is conducive to reducing the penetration of gas molecules.

Figure 2 shows the water vapor permeability of the blend.It can be seen from the figure that among all blends, the water vapor permeability of the blend with pp-G-Mah added is better than that of pure PP and blends without compatibilizer, and the water vapor permeability of the blend with 2.5% PP-G-MAH added is the worst, indicating that the interface performance of the blend is improved after the addition of PP-G-MAH.Increased its barrier to water vapor.

Fig.1 SEM images of 60%PET and 40%PP blends (1) and 60%PET, 37.5%PP and 2.5% PP-G-MAH blends (2)

Fig.2 Water vapor permeability of various mixtures, pure PP and pure PET