Incorporation of thermoplastic in situ polymerisation in double diaphragm forming

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Incorporation of thermoplastic in situ polymerisation in double diaphragm forming

Host Institutions: The University of Nottingham, University of Edinburgh

Start Date: 1st April, 2020

Duration: 6 months

Lead Investigator: Andrew Parsons

Co-Investigators: Adam Joesbury, Conchur O’Bradaigh, James Murray, Lee Harper

Aims

This project will specifically consider the use of thermoplastic resin in the RIDFT process. In situ polymerisation of thermoplastics is an area of increasing interest. Using liquid thermoplastic monomers with very low viscosity (~1 cP) in combination with the RIDFT process presents an exciting opportunity to create huge thermoplastic structures without the need for an autoclave or a press. Further, thermoplastic matrices offer additional benefits by enabling second stage forming (e.g. local incremental forming to enable more complex geometries) and can be welded to create larger assemblies. Within this 6-month project, the RIDFT process will be applied to Nylon 6 using in-situ polymerisation, which could be adopted for other thermoplastic resins in the future. The project will, on a small scale: (a) establish the ability to infuse a flat fabric constrained in a flexible vacuum system (between two diaphragms), (b) determine whether the presence of the resin improves forming of the fabric and (c) determine the heating requirements to polymerise the resin after forming.  

Nylon was selected as the initial matrix material as carbon/PA6 is of increasing interest in the automotive sector and in situ polymerisation of nylon is an established competency within the hub (Edinburgh). Technically, nylon monomer is a waxy solid, and so the infusion process could be quenched to reduce the chance of liquid spillage in the RIDFT process. Additionally, the waxy state may form more effectively than the liquid, with less chance of squeezing out material and causing e.g. corner thinning. Finally, the nylon curing reaction is heavily exothermic and can potentially progress with minimal additional heating.  

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