Envalior is introducing Durethan FLX-RTM, a new impact-modified PA6 material with high flowability, designed for rotational molding of tank liners. The material provides very good mechanical properties at low temperatures and has been specifically developed for manufacturing tank liners using the rotational molding process. In cooperation with rotational molding specialist Elkamet from Dautphetal, Germany, the material has already been successfully processed into prototype tank liners.
The new material complements the existing Envalior portfolio of plastics for various liner production processes. Durethan FLX-RTM addresses the growing importance of rotational molding in tank manufacturing, combining the cost-efficiency of a single-stage process with the ability to obtain homogeneous parts with complex geometries. At the same time, it retains the properties that characterize Durethan PA6 compounds used in injection molding and extrusion blow molding.
Rotational molding without weld seams and pinch-off lines
Rotational molding offers a cost-efficient, single-stage manufacturing process in which homogeneous parts are produced without the pinch-off lines typical of extrusion blow-molded liners and without weld seams required in multi-part injection-molded designs. For tank liners, this allows potential weak points in the structure to be reduced and simplifies the component design.
As Envalior emphasizes, the Durethan FLX-RTM compound is heat stabilized and shows high melt flowability, which facilitates the molding of complex features with screw threads and the integration of metal or aluminum inserts such as bosses. At the same time, the material maintains the key advantages of Durethan PA6 compounds known from injection molding and extrusion blow molding applications.
Material parameters for hydrogen applications
Durethan FLX-RTM is a heat-stabilized, impact-modified, easy-flow PA6 compound based on low-molecular-weight polyamide 6, offering very good flow properties. Despite the reduced molecular weight, the material maintains high mechanical strength thanks to advanced impact-modification systems and heat-stabilization packages.
The key performance parameters of Durethan FLX-RTM include:
- low hydrogen permeability, providing a high barrier against small gas molecules,
- compatibility with liquid fuels, including CE10 gasoline and other apolar liquids,
- high toughness at temperatures down to –40 °C,
- high elongation and ductility.
The combination of these properties supports the design of safe and durable tank liners for a range of storage media and environmental conditions, particularly in the area of hydrogen storage.
From material development to prototypes
In cooperation with Elkamet, a specialist in technical plastics processing with long-standing experience in rotational molding, blow molding, and extrusion, Envalior has produced several prototype parts using electrically heated molds, vacuum assistance, and nitrogen purging. These process solutions were used to translate the material properties into high quality of the finished parts.
Elkamet has many years of experience in transferring projects from prototype stage to series production and extensive expertise in hydrogen storage vessel manufacturing. The company supports customers in improving part design and optimizing mold construction to achieve fast and efficient production.
Integrated customer support throughout the development process
Envalior and Elkamet offer manufacturers a wide range of services at all stages of component development. This includes consulting on design, processing, and manufacturing technologies, built up over many years in applications involving plastic liners for high-pressure tanks of various sizes, designs, and media.
An important advantage of Envalior is its extensive database on hydrogen permeation through materials, which few material suppliers provide. With this data, customers can analyze how permeation depends on pressure, temperature, and wall thickness and can optimize liner design according to application requirements. Envalior also provides detailed material data on mechanical behavior and processing properties and offers on-site support for process optimization and series-production startup.
Additional information on Envalior materials is available via the MaterialAdvisor platform, which provides digital tools and services to support the search, selection, and evaluation of materials for specific applications.
Rotationally molded prototype liner produced by Elkamet using Envalior's Durethan FLX-RTM. The easy-flow PA6 compound enables uniform wall thickness, integration of boss features, and high mechanical performance for hydrogen storage applications.
