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Developing Welding Processes for Structural Thermoplastic Composites

Project Code: 0905-11

Research Need

In the move towards sustainable ‘cradle to cradle’ manufacturing solutions, thermoplastic composites offer numerous intrinsic advantages over their thermosetting cousins. Due to their non cross linking architecture, they can be formed and reformed without degradation. As well as this, the joining techniques used allow for easy disassembly. However, whilst joining of thermosets is well understood, the joining of thermoplastics is holding back their application. It is in the joining of thermoplastic composites that this project will focus.

Whilst it is often stated that thermoplastic composites can be reformed and reprocessed, there is little easily accessible information of the details of these processes.

As well as this, it has recently become possible to recycle thermoset composites but little work has been carried out into the recycling of thermoplastic composites.


Review of joining technology (especially welding) and sustainability of continuous carbon fibre thermoplastic composites.

Selection of the three most industrially applicable processes and manufacture of representative specimens.

Review of recycling and reprocessing technologies for continuous carbon fibre thermoplastic composites.

Project Outline

Building on a world leading reputation in the joining of thermoplastic composites that TWI held in the 1980s, this project will revisit the state of the art from which it will investigate three joining technologies. These will be selected on the basis of ease of processing and disassembly.

In addition to this, a state of the art review on the reprocessing/reforming of thermoplastic composites will be considered with a view to process innovation.

Finally, the recycling of thermoplastic composites will be considered with a State of the Art review with a view to process innovation considering using microwave technology for example.

Based on the above, a suitable demonstrator will be produced incorporating some of the findings.

The project will focus on carbon fibre reinforced thermoplastic composites of PEEK and PEI.

Relevant Industry Sectors

All industry sectors which apply composite materials (e.g. aerospace, automotive, marine, military, etc).

Technical and Economic Benefits

Increased sustainability - Possibility of recycling or reusing welded thermoplastic composite parts through disassembly.

Reduced costs - optimisation of welding processes focussing on energy and time saving.

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