The Smart fortwo is the first commercialized car to have full body panels made from polypropylene.
Borealis Ag in Austria developed Daplen ED230HP, a thermoplastic polyolefin (TPO) compound, to meet the cost-effective production targets and aesthetic, safety and environmental requirements set by Smart fortwo designers.
Daplen ED230HP replaces polycarbonate polybutyleneterphtalate (PCPBT) that traditionally serves in body panels, such as bumpers, side panels, tailgates, and hoods. To ensure a smooth transition to the new material, Borealis worked closely with Smart and their Tier One supplier Plastal to provide engineering and simulation support in addition to the material development.
The TPO is an in-mass colored compound: Colors are blended into the compound to provide a ready-made base coat. As a result, post-assembly painting steps are reduced with only a painted clear coat layer needed. The UV resistant TPO adheres well to paint and thus helps ensure quality aesthetics over the long term. But if the vehicle is damaged, owners will see lower painting costs when it's repaired.
The lightweight TPO also let designers shave 15% off the vehicle's weight which will in turn help reduce fuel consumption and carbon dioxide emissions. Furthermore, the material is fully recyclable in line with European legislation.
Daplen ED230HP's low thermal expansion creates zero gap tolerance between parts. The material's good impact/stiffness ratio for the injection molded panels leads to improved driver safety.
"Smart's pioneering approach to using polypropylene for full body panels in its fortwo series is a major step forward for the automotive industry and its suppliers," says Paul Turner, Vice President of Automotive and Appliances at Borealis. "Daplen ED230HP helped Smart tighten its production process while raising the environmental, aesthetic, and safety performance of its vehicle."