CompositesWorld

MAR 2017

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MARCH 2017 32 CompositesWorld FEATURE / COMPOSITES an SMC developed using Zoltek's (St. Louis, MO, US) Panex35 commercial carbon fiber, compounded at its Grabill, IN, US, plant and available for sale to other molders. Initial appli- cations were structural. All Magna Exteriors composites operations were acquired by CSP in July 2014, making CSP the world's largest SMC fabricator. "Our approach is to put carbon fiber where it makes sense," says CSP's Siwajek, "for example, using hybrids with glass fiber where the carbon is for reinforcing structures. rough design, you can get the best bang for your buck, and achieve unique, cost-effective solutions." Polynt Composites Germany (Miehlen) has offered CF-SMC since spring 2016, targeted initially to structural applications but with Class A products in development. "Our Polynt- RECarbon products are reinforced with recycled carbon fiber mats," says product development manager Nicole Stoess. "We also offer Polynt- SMCarbon (3K-50K) SMC in both epoxy for autoclave processing, and epoxy and vinyl ester SMC for compression molding." She notes further that "several, well-known European automotive companies have expanded their use of CF-SMC significantly enough that Polynt has recently added a new 1.5m-wide SMC machine, fully dedicated to customized carbon fiber materials." Covering all the composite bases "What I see for 2020-2025 models is hybrid materials," says Lownsdale, who clarifies, "not just combining steel with aluminum and CFRP, but a combination of thermoplastics, thermosets and carbon fiber." He notes, as and example, a decklid using injection molded thermoplastic for the outer panel and RTM'd CFRP for the inner panel, adding, "is approach works in hoods and roofs also. Processes that never appeared to be similar, we can now combine." CSP also has produced a Class A panel with RTM CFRP inner, but this one with a TCA Ultra Lite SMC outer, developed by its European R&D; group. "ey won a 2016 CAMX award for this multi-material decklid which uses recycled carbon fiber material," Siwajek relates. "ey reworked a traditional SMC part to cut weight by 13% vs. aluminum." e parts were molded in less than 3 minutes using a fast-cure epoxy resin from Hexion (Columbus, OH, US). "ese low-cycle-time resins put RTM on par with SMC," claims Siwajek, noting that Teijin Ltd.'s (Tokyo, Japan) recent purchase of CSP is October for the first compression-molded carbon composite hood on a produc- tion vehicle. e bonded, two-piece hood for the 2016 Cadillac ATS-V and CTS-V sedans uses fast-curing carbon fiber/epoxy prepreg. Six plies of 50K uni carbon fiber are used for the outer panel, and a fabric weave is used for the inner panel, both from Barrday Composite Solutions (Millbury, MA, US). e hood weighs 27% less than an aluminum version. Robotic preform and material loading processes reportedly help drop cycle time below 10 minutes, enabling volumes up to 30,000/ year. e hoods are painted, with an option for exposed weave on the inner panel. Magna's above announcement followed its launch of EpicBlendSMC EB CFS-Z, SIDE STORY Intended to develop composite body panels that could store and release energy like a battery, the European Union-funded project STORAGE (2010-2013), led by Imperial College (London, UK) and Volvo Cars (Gothenburg, Sweden), demonstrated a structural supercapacitor roof and a trunk lid with supercapacitor laminates that cut weight 60% compared to existing components. The recharge- able panels comprise multiple layers of carbon fiber/epoxy insulated by fiberglass inserts (see above). Parts were made using Solvay (Woodland Park, NJ, US) MTM47 out-of-autoclave prepreg. A variety of material approaches were investigated for efficient energy transfer, including carbon aerogel reinforcement of carbon fibers and multifunctional matrices (e.g., 50/50 weight mixtures of epoxy resin and ionic Li salt solution). Volvo claims such panels could power its S80 hybrid demonstrator vehicle's 12-volt electrical system. Project teammate Swerea SICOMP (PiteƄ, Sweden) has filed patent applications for carbon fiber batteries. There also has been an increase in car models with photovoltaic solar panels in the roof. "The military has been developing battery panels and embedded solar panels for years," says Gary Lownsdale, president of Trans Tech Intl. (Loudon, TN, US). "Again, hybrid composite materials offer a lot of opportunity, for example adding carbon nanotubes and other nanomaterials. Embedding flexible electrical circuits in body panels is also an attractive development because you can get rid of the wiring harnesses and simplify the supply chain and assembly." Composites in Class A body panels: Integrating energy storage Multifunctional composite Led by Imperial College and automaker Volvo, the STORAGE project demonstrated a structural supercapacitor roof and a trunk lid with supercapacitor laminates that cut weight 60% over existing components. The rechargeable panels comprise multiple layers of epoxy-impregnated carbon fiber insulated by fiberglass inserts. Source | Volvo Cars

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