With Tepex, LANXESS is one of the leading manufacturers of fiber-reinforced thermoplastic composites for lightweight and highly mechanically elastic structural components. The specialty chemicals company offers a family of composite materials called Tepex flowcore for use in a variety of compression molding processes. This product range has now been expanded and optimized. The new composites are designed as replacements for thermoset sheet molding compounds (SMCs). They have similar mechanical properties and are more ductile. Also, as a thermoplastic material combination, Tepex flowcore is easier to recycle than SMC. They are easy to process because they are formed only by thermal methods. Sabrina Anders, Tepex flowcore project manager at LANXESS' Performance Materials business unit, said: "We use Tepex flowcore mainly for large underbody parts and loading bays in automobiles, but also for parts such as large housings and battery covers. Tepex flowcore is already in series It has proven its worth in production, such as in the bumper beams of a Japanese automaker's mid-size sedan."
Diverse range
The matrix of the new sheet composites is based on polypropylene, polyamide 6, polyamide 12, thermoplastic polyurethane or flame retardant polycarbonate. The matrix is reinforced with long fibers rather than continuous fibers in Tepex dynalite. These fibers can be up to 50 mm long and are distributed throughout the matrix in the form of cut fibers of constant length. Tepex flowcore is available with glass fibre or carbon fibre reinforcement.
Quasi-isotropic mechanical properties
Under the right processing conditions, parts made from the new lightweight material can exhibit nearly the same bending stiffness as their counterparts in the Tepex dynalite family, and they are much stronger than injection-molded materials typically reinforced with short fibers many. Depending on the processing method and part design, the fibers can be aligned in one preferred direction or completely random. "The components can be designed so that they exhibit quasi-isotropic mechanical properties; in other words, nearly identical in all directions," Anders explained.
Numerous processing options
The new composite materials have great versatility in processing methods. For example, they can be compression molded with standard tooling for long fiber or glass fiber reinforced thermoplastics (LFTs and GMTs). They can also be used in existing thermoset sheet molding compounds and tools. "They have such good flow properties that they can reproduce the fine areas of the part very accurately, like the rib structure, and can make the walls very thin," Anders said. Tepex flowcore and Tepex dynalite can also be used together in compression molding processes, Due to their identical polymer matrix, they exhibit excellent adhesion to each other." This opens up the opportunity to use Tepex dynalite to reinforce specific areas of the part that are particularly stressed, and at the same time, to use Tepex flowcore in a cost-effective way Integrate features such as guides and brackets. Another benefit is that processors can get all of these composite semi-finished products from one place without having to combine materials from different manufacturers. "Anders added.
The new composite material – much like Tepex dynalite – is also well suited for the hybrid molding process. This involves moulding them in an injection moulding tool and then imparting their features by injection moulding in a single process. The production of bumper brackets for this Japanese sedan went a step further. The structural part is made of Tepex flowcore and Tepex dynalite, moulded and functionalised with a Durethan brand polyamide 6 compound.