JEC World 2019: Evonik
Curing agents and cores specialist Evonik introduced two new products at JEC. VESTALITE S is a styrene-free curing agent for high-performance epoxy sheet molding compound (SMC), based on Evonik’s diamine chemistry. It offers low initial viscosity for high fiber mass fraction and good fiber wetting. It cures in just 3 minutes at 150°C. VESTALITE S, notes Leif Ickert, crosslinkers senior manager at Evonik, is lighter weight than polyester SMC and, because it is stiff at room temperature, easier to handle than polyester SMC (see photo).
Exemplary parts of this material at the Evonik stand were a carbon fiber/epoxy SMC wheel for an electric multi-purpose city vehicle (450 kilograms without battery), and a glass fiber/epoxy SMC developmental lift gate fabricated for a South Korean automotive OEM (see photo). Fabrication of these parts was coordinated by Vestaro, a joint venture of Evonik and Forward Engineering, with compounding provided by Donsung Corp. for the lift gate and Polytec Group for the wheel. Dongsung used advanced SMC equipment by Ilsung Korea to increase material performance.
Ickert commented at JEC that SMC is appealing because it is an established technology and allows OEMs to use existing presses, thereby avoiding the capital expenditure associated with integration of composites manufacturing operations.
Also new at the show was VESTALITE P 312 and VESTALITE P 342, both of which are 1K polyurethane formulations for prepreg compression molding (PCM) materials. P 312 brings the combination of low shrinkage, UV stability and high intrinsic toughness that allows a broad application potential from high quality composite exterior surfaces to PCM made leaf springs. P 342 is designed for composite-metal hybrid manufacturing and reportedly has improved adhesion to metal. Both VESTALITE P grades offer long shelf life at ambient temperatures and quick cure (5 min at 150°C)
A look at the process by which precursor becomes carbon fiber through a careful (and mostly proprietary) manipulation of temperature and tension.
Fiber-reinforced plastic (FRP) replacing coated steel in more reinforced-concrete applications.
For composite applications, these hollow microstructures displace a lot of volume at low weight and add an abundance of processing and product enhancements.