Kautex Blow Molds 320-Liter PA Liner for Hydrogen Containers

German firm Kautex Maschinenbau’s blow-molding experts have successfully produced a large-volume polyamide liner for hydrogen pressure vessels by means of extrusion blow molding. The liner is more than two meters long (6.5 ft), with a diameter of approximately 500 mm (1.6 ft) and a volume of 320 liters (84.5 gal). This is reportedly the first time a liner for a hydrogen container has been produced in this size via blow molding. Hydrogen presents considerable challenges in relation to the liner material’s permeability. Being the smallest molecule in the periodic table, hydrogen can diffuse through virtually every plastic. Special polyamides (PAs) have the best barrier properties. However, due to their low melt rigidity and complexity, these PA variants have been difficult to process on this scale by blow molding. Newly developed PAs and a special extrusion technique have now made this possible.