Extrusion International 3-2020

46 Extrusion International 3/2020 EXTRUSION BLOWMOLDING Hydrogen presents considerable challenges in relation to the liner material’s permeability. Being the smallest molecule in the periodic ta- ble, hydrogen can diffuse through virtually every plastic material. Spe- cial polyamides (PAs) have the best barrier properties. However, due to their low melt rigidity and com- plexity, they have previously been difficult to process on this scale by blow molding. Newly developed polyamides and a special extrusion Producing 320-Liter Hydrogen Liner in Blow Molding Process vessels (CPV) for various applica- tions such as hydrogen, CNG and LPG tanks. Composite tanks consist of a thermoplastic liner, a boss part, to which the valve is connected, and a fiber winding which adds mechani- cal strength. The internal liner is pro- duced by blow molding. CPV high-pressure containers for hy- drogen are generally designed for an operating pressure of 700 bar and a burst pressure of 1750 bar. The liner is a core component of the container. technique have now made this pos- sible. “Producing a liner of this size from polyamide has been a major chal- lenge. The work we are doing here is truly pioneering”, said Abdellah El Bouchfrati, Head of Kautex’s Com- posite Business Development, where the new hydrogen liner was devel- oped. For some time now, Kautex has been putting its efforts into on-going de- velopment of composite pressure Kautex Maschinenbau’s blow molding experts have successfully produced a large-volume polyamide liner for hydrogen pressure vessels using extrusion blow molding. The liner is more than two meters long, with a diameter of approximately 500 mm and a volume of 320 liters. This is the first time that a liner for a hydrogen container has been produced in this size by blow molding Prototype production in the Kautex Composite Center (All pictures © Kautex Maschinenbau GmbH) Blow-molded PA liner 320 l hydrogen pressure vessel