Thermoplastic composites, a genuine alternative to thermoset composites
Thermoplastic composite materials boast outstanding characteristics, making them increasingly valuable in many sectors, including automotive and aerospace.
Lighter than traditional materials such as glass or metal, composite materials (both thermoset and thermoplastic) help reduce the weight of structures, a major challenge for the automotive and aerospace sectors in particular. Composites also have the added benefit of inalterability, making them reliable materials for exacting markets.
Composite materials comprise three main constituents:
- Reinforcement: framework concentrating the core mechanical properties of the finished product,
- Organic matrix: resin binder providing cohesion of the structure and transmission of forces towards the reinforcement,
- Optional additives: to modify or improve the resin’s properties.
The matrix defines the nature of the composite, i.e. thermoset (mostly epoxy, unsaturated polyester, vinyl ester), or thermoplastic (PEKK, acrylic, polyamide, PVDF or polypropylene). Unlike thermoset resins, thermoplastic resins are generally in a solid state at room temperature. Only Arkema’s Elium® acrylic resin is a liquid thermoplastic resin at room temperature.
Fast RTM Project: for mass-produced lightweight, sturdy and durable composites parts
In partnership with the M2P Institute of Technology Research in Metz and several French carmakers and automotive OEMs, Arkema joined the Fast RTM - Fast Resin Transfer Molding - Technology Plateform in 2015. It demonstrates the feasibility of mass-production automotive parts made of Elium® composite, at the speed of one part every two minutes.
A winner for process technology at the most recent JEC Innovation Awards, Fast RTM is expected to run through December 2017. And pave the way for lighter, lower-carbon-emission vehicles featuring “Made by Arkema” thermoplastic composites.
Invaluable benefits to meet the latest challenges
With performances matching those of thermoset composites, thermoplastic composites help design technical finished products.
However, whereas thermoset composites raise questions on their lifecycle and environmental impact, thermoplastic composites provide genuine solutions thanks to their inherent properties:
- Recyclability: thermoset composites are manufactured from thermoset resins (primarily epoxy and polyesters), which makes them difficult to recycle as they cannot be modified after polymerization. Thermoplastic composites by contrast can be processed and converted after crushing, thereby minimizing waste and so meeting increasingly stricter environmental requirements.
- Thermoforming: once formed, thermoset resins cannot be further shaped: the product remains as it was designed. In the case of thermoplastics, the product can be shaped by heating it up a little, which softens the material.
- Thermowelding: when assembling parts made of thermoset composites, these require bonding, which raises issues of heterogeneity of materials. As thermoplastics can be heated up, the materials can be welded, a process that may prove less costly and simpler for manufacturers to handle.
A large number of industrial applications
As they can replace metal or glass as well as thermoset composites, thermoplastic composites are suitable for a wide range of applications:
- Automotive: structural parts for car body and seat components,
- Truck/bus/farming machinery: body parts and structural parts,
- Sport: ski, snowboard, skateboard, footwear,
- Marine industry: hull, boom and other components on the bridge (sailing boats, motor boats),
- Electronics: computer and cell phone casing,
- Wind power: turbine blade, nosecone, nacelle.
Thermoplastic composites were developed from a recent breakthrough innovation. All feasible applications have certainly not been conceived yet: a huge opportunity for the most far-sighted manufacturers.