CompositesWorld
Issue link: https://cw.epubxp.com/i/620463
8 CompositesWorld PAST, PRESENT & FUTURE JANUARY 2016 the same as steel. The rebar is intended for flat concrete slabs that require no special shapes, stirrups or onsite bending. Another is a new cooperative venture between Wabash National (Lafayette, IN, US) and Structural Composites (Melbourne, FL, US), under which Wabash will manufacture a new composite refrigerated truck trailer that is close to cost parity with aluminum (the technology was on display at the recent CAMX 2015 show, and a CAMX award candidate). Low-cost polyester resin is tweaked for better performance, using urethane, and low-cost, of-the-shelf structural preforms are combined with a thin laminate in a patent-pending assembly line that delivers a lighter-weight yet still durable solution. Wabash believes in the concept to the extent that it is building a new production line to produce the panels. If composites are to expand into automotive platforms, then this cost parity trend is an absolute necessity. For many years, I've sat in keynote sessions at the Society of Plastics Engineers (SPE) Automotive Composites Conference and Exhibition (ACCE) and heard OEMs say that the value proposition isn't there — yet — for composites. But this year, a "yes, it is" example came to light. Automotive specialist Antony Dodworth, managing director at Bright Light Structures (Peterborough, UK), exhibited an all-carbon fber composite chassis tub, using recycled carbon fber, (see photos, top left) for British kit-car maker Zenos (Norfolk, UK). The fve-piece tub can be made quickly (less than 15 minutes) and features a very inexpensive plastic core that's crushable, enabling thermoforming of the tub elements. The Zenos E10 car is not a fancy supercar but an afordable (kits from £24,995) sports convertible that costs less than just about any comparable sports car on the market today. Cost parity — hope that trend continues. Crossing the thermoplastic/thermoset divide By Ginger Gardiner, CW Senior Editor ginger@compositesworld.com As composites move into high-production industries, there is a need for shorter molding cycles and recyclability. In the automotive sector, for example, 85% by weight of end-of-life vehicles in the European Union must be reusable or recyclable as of Jan. 1, this year. Thermosets crosslink as they cure, ofering high structural performance and lighter weight. They also ofer the low viscosity necessary to thoroughly wet out fber reinforcements — essential for those high mechanical properties. Thermoplastics can be processed very quickly but their high viscosity, low temperature resistance and moisture uptake at the amorphous, engineering polymer end of the spectrum cause problems. At the high-performance end, the issues are control of cool down for the required crystalline structure and high cost. What the industry needed was resin systems that combined the positives of each but avoided the negatives. In 2014, Arkema (Colombes, France and King of Prussia, PA, US) launched Elium reactive liquid acrylic thermoplastic resins, which boast low viscosity (100 cps) at room temperature, enabling resin injection without heating in resin transfer molding (RTM), high-pressure RTM (HP-RTM) and infusion. Elium composites attain mechanical properties comparable to epoxy without post-curing but boost toughness by 50% and are recyclable, weldable and thermoformable at 200-220°C. Cure times range from 20 minutes to a few hours at room temperature, but drop to 30-120 seconds at temperatures above 100°C. Recycling has already been demonstrated and water pickup is only 0.5% vs. polyamide's typical 5-10%. Also launched in 2014 is Connora Technologies' (Hayward, CA, US) Recyclamine hardener, which applies photoresist chemistry (now common in microchips) to epoxies, enabling a cleavable bond to be programmed into the resin so that, under specific conditions (e.g., pH level or light) crosslinks can be broken, leaving recyclable