How Oppera™ modifiers improve BOPP film performance
Oppera™ modifiers are miscible with polypropylene (PP) at melt processing temperatures. As molten PP cools, crystallites begin to form in a semi-crystalline polymer. Then, as the PP crystallizes, the crystal lattices reject the Oppera modifier that concentrates in the amorphous domains.
- As the Oppera modifier diffuses away from the crystalline regions, it inhibits the crystal growth. This enables the production of smaller crystallites and better optical properties such as high clarity and low haze.
- Small molecules, e.g., water, oxygen present in the air, cannot penetrate the crystalline PP regions so they have to diffuse through the free space located between the PP molecules in the amorphous domains. But the presence of Oppera there reduces the permeability of these small molecules : the barrier properties of the film is improved.
- As Oppera modifier concentrates in the amorphous domains, it raises the overall glass in temperature (Tg) in this region. As the overall Tg is now above room temperature, this effect increases the barrier to diffusion as well as the stiffness.