Car manufacturers are increasingly looking to lower the carbon footprint of their vehicles; not just the carbon created in the vehicle’s road-going lifetime but also the footprint created by the vehicle’s manufacture and its end of life recyclability.
Total, the French-based petrochemicals group, has built a technology demonstrator that it thinks may be the city car of tomorrow. The Total Car Concept was first revealed at the Frankfurt Motor Show in 2011, with a revised prototype shown at the Mondial de l’Automobile in Paris in 2012 which, according to Total, sparked even more interest than the original concept.
Speaking at ARMO, the rotational moulding conference in Lyon in October 2012, Eric Maziers, research and development manager of Total Belgium, was at pains to point out that Total was not planning to rival Ford or GM.
“Total will never produce cars, we just produced a demonstrator,” said Maziers.
The car showcases a number of innovations from various companies, including novel battery technology, a carbon fibre roof structure and adhesive bonding of components. But it is the construction of the car body itself that lends itself particularly to rotational moulding.
The body was moulded in Italy by Persico, the rotational moulding machinery manufacturer, with technical assistance from Queen’s University’s rotational moulding research manager, Mark Kearns.
The body is made from a three-layer structure. The skin is made from Total’s bio-TPSeal material. Bio-TPSeal was developed from the original TPSeal material intended for use in fuel tanks. To meet US import regulations Total had to find a way of bonding PE with Arkema PA 11.
Mark Kearns explained: “The PE that’s used to adhere to the polyamide has some very specific melt characteristics. And you can put a blowing agent inside to make an extremely thick, regular foam structure. That means it opens up sandwich constructions for very, very large parts.”
BioTPSeal is an alloy made from TPSeal and polylactic acid (PLA) made by Futerro, a 50:50 JV between Total and Galactic, the world’s largest producer of lactic acid.
Eric Maziers said: “The use of rotomoulding processes combined with bio-TPSeal technology allows us to reduce the impact at each stage of vehicle life by sing much fewer elements: no welding, lower weight, less CO2, less maintenance.
“Being green is good but there has to be new properties. Bio TPSeal has very good foaming qualities.”
Mark Kearns explains: “Using conventional PE materials you get these voids, you just will not be able to get the structure you want. We were able to get these very thick structures, so we get the impact values we need.”
The concept car has been subjected to impact tests since the winter of 2011. Maziers said: “We did a lot of testing. We did static tests, crash tests. You need to do this if you want to convince the car industry.”
While it is these foaming characteristics that make the concept car crash safe, working with these foaming qualities can be an art. Kearns said that testing of the materials in a monolayer and then combining them into a three-layer structure, was actually quite difficult to do.
“The timing’s important – when you add the second layer; the third layer; how the materials start to foam… you have a very solid melt, a very heavy layer on a soft foaming layer; the encapsulation of the gas, the timing and the cooling are all very important.”
Foaming is not the only attractive quality of the TPSeal. It is sustainable, has improved stiffness, improved surface gloss and unlike regular PE, bio-TPSeal is paintable and can therefore receive a proper automotive finish.
As the pressure of EU Regulation 443 looms – setting a target average CO2 emission of 95g/km across a car company’s entire range of 2020 – it is no wonder that the car manufacturers are eyeing this concept with interest.