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23. June 2006

Polycarbonate blends for automotive body parts

Polycarbonate blends such as Makroblend (PC/PET or PC/PBT) and Bayblend (PC/ABS) from Bayer MaterialScience AG are increasingly suited to applications in the field of automotive body parts. For example, mineral-reinforced PC/PET and PC/PBT blends as well as unfilled and PC/ABS formulations reinforced with glass fibre are increasingly being used instead of sheet molding compounds for the production of rear spoilers and antenna covers. Examples of this trend are the rear spoilers of Volkswagen’s Golf GTI and Polo GTI and the Alfa Romeo 159, which are injection molded using Makroblend DP 7665. The PC/PET blend is said to be a more cost-effective solution, particularly with large production runs because, unlike the corresponding SMC components, the resulting parts need no secondary finishing to remove ridges and flashes. Instead Class A surfaces are produced that can be painted without any pre-treatment.

Another advantage of the PC/PET blend is that due to its low density, it yields much lighter components than SMCs. In addition, being injection molded, it allows undercuts, which means greater freedom of design. This is not possible with SMCs that are processed by press molding. Its linear thermal expansion is also low enough to achieve narrow gaps between assemblies.

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