Eyes have been on polycarbonate window glazing as the material most likely to replace glass in car fenestration, but another clear, durable thermoplastic—acrylic—is making news with its debut as the replacement for glass in the windshield in RED Motorsport's Lotus Exige racecar.
The polymethyl methacrylate (PMMA, or acrylic) used is supplied by Evonik, which also happens to be a sponsor of the RED Motorsport team. But company officials insist this sponsorship is not what created the material replacement opportunity; in fact, PMMA just plain beat glass on performance. Evonik (Hanau, Germany) insists, also, that live tests on racecars are the start of what they anticipate will be PMMA's eventual use for series production of "normal" vehicles.
Rudolf Blass, responsible for automotive and surface design in Evonik's Acrylic Polymers Business Line, says the stone chip resistance, for example, is much better than in a comparable windshield made of glass. What is more, PMMA reduces the weight of the windshield by as much as 40%, from 11 kg to just 6 kg.
Other characteristics of the material also made helped get approval for the switch, including PMMA's rigidity, transparency, acoustic properties, and high UV and weathering resistance. It also has a lower infrared transmission than glass, so the passenger compartment stays cooler. The developers at the plastics supplier have their eye on further applications such as the glass for rear windows or panoramic roof panels, which they say may be ready for series production shortly.