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Re-use of Thermoplastic Composite

Periodic Reporting for period 2 - RESET (Re-use of Thermoplastic Composite)

Reporting period: 2017-01-01 to 2018-04-30

Current European policies plead for new technologies capable to implement feasible processes for recycling of products in their end of life cycle. Within this framework, the re-use of thermoplastic composites, is a recurrent topic within the aircraft manufacturing industry which needs a suitable solution for the high performance thermoplastic composites once the craft is dismantled. PEEK (Polyether ether ketone) and PPS (Polyphenylene sulphide) all together reinforced with CF (Carbon Fibre) are the most common high performance materials considered as leftovers when their lifecycle has come to an end.
Taking this into account, the RESET project aims to bring a second life to those thermoplastic composites which have been condemned to landfills, to the carbon fibre recovery by means of polymer pyrolysis or to energetic recovery. This milestone will be achieved through a sorting and milling process of these materials, leading to short chopped fibre reinforced thermoplastic granulates. These conditioned leftovers will be subsequently used to obtain new reinforced thermoplastic composites, by melt compounding along with virgin polymer, considering both monocomponent as well as binary blends.
In the first Work Package, the waste material was studied to ensure a correct material selection. Specific characteristics were defined along this task based on different sorting criteria:
- Thermoplastic matrix (PEEK and PPS)
- Chemical nature of reinforcement (carbon fibres)
- Reinforcement shape (Short/long fibre, woven, nonwoven)
- Fibre content (Polymer to fibre ratio)
Taking as starting point these properties, a table of criteria was developed and the scrap material from part manufacturers was selected as the main source of waste stream.
The main objective of Work Package 2 was the conditioning and characterization of the recycled material and the development of a new family of different composites with recycled CFRP based on Polyphenylene sulphide (PPS) by means of extrusion process, as well as, the characterization of the prepared composites. During Work Package 3, the definition of the manufacturing process by injection moulding and thermoforming was established. The composites prepared during WP2 were used to produce halterio specimens by injection and thermoforming. These specimens were characterized by different techniques, in order to ensure the feasibility of the recycling process. In the last technical Work Package (4), different prototypes were produced by means of injection and thermoforming. The project has successfully proven the possibility of recycling CFRP and produce new parts for aircraft. Thus replacing the use of metal parts in the airplane and, reducing the consumption of raw materials. A direct impact is expected in terms of sustainability, cost reduction, fuel consumption and CO2 emissions.
The RESET project aims to bring an efficient technology of recycling high performance thermoplastics. The success will be sustained by an appropriate sorting of waste streams, followed by a comprehensive conditioning process by means of cryogenic milling. This technology enables the brittle rupture of the thermoplastics composites lowering the overall temperature of the process. This, direct echoes over key parameters for further processing, offering control over:
- Particles size (up to micron scale)
- Particle size distribution (homogeneous distribution)
- Particle shape (brittle rupture)
Therefore, the obtained conditioned waste presents optimum specifications in order to be incorporated to the subsequent compounding step.
Therefore, the RESET project will lead to a new generation of recycled materials that are expected to be classified half way engineering and high performance polymers within the pyramid of materials.