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BMW i8 uses Tepex composites for rear muffler cover
“Engineers increasingly are using Tepex performance composites from Lanxess subsidiary Bond- Laminates to significantly improve the mechanical strength of components made of fibre reinforced thermoplastic compression molding compounds,” Lanxess says.
It adds, “The latest example is a cover on the rear muffler of the BMW i8, which is fabricated in a direct long fiber thermoplastic (DLFT) process from a polypropylene compression molding compound reinforced with long glass fibre rovings.”
An insert made of Tepex dynalite 104-RG601 is used as the surface layer and with its stiffness at high temperatures; it ensures that the cover undergoes no deformation or failure in the hot environment of the rear muffler and also improves impact resistance of the component in freezing temperatures.
The Tepex insert is 0.5 millimeters thick and made of a polypropylene matrix, incorporating 47 per cent by volume continuous glass fibre rovings as a single-layer fabric and due to this insert, the stiffness of the cover increases by a factor of four at room temperature and a factor of six at the operating temperature of the rear muffler.
“In penetration tests to DIN EN ISO 6603-2, the Tepex dynalite formulation used proved to be eight to nine times more impact resistant at room temperature than a DLFT compression molding compound based on polypropylene,” Lanxess explains.
“At temperatures of -30°C, the impact resistance is even 10 times higher. DLFT based on polypropylene will splinter under these conditions in a crash, our Tepex will not,” Harri Dittmar, composites expert at Bond-Laminates said.
Lanxess informs that Tepex also is an attractive option for locally reinforcing components made of other thermoplastic compression molding compounds and forming materials.
It explains that the mechanical properties of Tepex-reinforced DLFT polypropylene materials are on par with glass-mat-reinforced and glass-fabric-reinforced thermoplastic systems (GMT and GMTex) based on polypropylene.
“In this case, the combination of Tepex with the DLFT process opens up considerable savings potential, for instance in the fabrication of underbody components,” Dittmar notes.
Polypropylene-based, low-weight reinforced thermoplastics (LWRT), which are used to manufacture underbody panels due to their high sound absorption, can also be significantly stiffened with Tepex surface layers.
Using a single-layer Tepex component preserves the acoustic effect. The result is components that can easily withstand the mechanical loads associated with road traffic.
Lanxess is a specialty chemicals company with sales of €8.3 billion in 2013 and about 16,700 employees in 29 countries and has 52 production sites worldwide and produces plastics, rubber, intermediates and specialty chemicals. (AR)