DuPont has developed a special grade of Selar® PA, known as 2072, which is specially designed for blending with EVOH. Selar® PA 2072 can be tumble-blended with most grades of ethylene vinyl alcohol copolymers to form blends that combine the excellent barrier properties of EVOH with the thermoforming properties, processing flexibility, and moisture insensitivity of Selar® PA. In addition, Selar® PA 2072 provides better adhesion in blends with EVOH than other grades of amorphous nylon, and this may allow convertors to employ less expensive adhesives.
Selar® PA barrier resin is packaged dry in moisture-proof packages at 0.125% maximum moisture and can be extruded directly. However, Selar® PA resin does absorb moisture and should be dried if the bags have been opened, the resin has been exposed to relative humidities of greater than 50% for 1/2 hr or more, or the melt temperature exceeds 282°C (540°F). Typical drying temperatures are in the range of 80 to 95°C (175 to 205°F).