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Cheaper, Lighter, Safer Composite Materials for Aircraft Interiors

Periodic Reporting for period 1 - IntAir (Cheaper, Lighter, Safer Composite Materials for Aircraft Interiors)

Reporting period: 2016-11-01 to 2017-10-31

What is the problem/issue being addressed
The aim of the IntAir project is to refine the materials and upscale the manufacturing process for a new generation of aircraft interior composites that are cheaper, lighter and safer than the toxic, carcinogenic materials that are currently used.
Composite materials are well-established for aircraft interior sidewalls, galleys, lockers and seating. To meet the strict fire and weight requirements for aircraft interiors, the current solution is to use a fire resistant composite made of phenolic (phenol formaldehyde) resin with carbon or glass fibre reinforcement. However, there are 3 major problems with phenolics:
• Cost: Phenolic parts have long moulding times and need several hours of manual finishing.
• Weight: The poor surface finish means that filler is needed, adding to the component weight.
• Safety: Phenolics emit toxic and carcinogenic materials during processing.

Why is it important for society
Most composite aircraft components are manufactured from prepreg, an intermediate material where the resin is pre-impregnated into a reinforcement fabric, for subsequent moulding into parts. Companies making components from phenolic prepregs are actively looking for alternative materials to reduce cost, reduce weight and remove health & safety concerns to their workforce. To date, there have been no materials that can offer all of these benefits.

What are the overall objectives?
As a direct substitute for phenolic, this project focusses on a prepreg using polyfurfuryl alcohol (PFA), derived from bio-resources, which offers the improvements in each of the 3 areas:
• Cost: A 34% reduction in moulding cycle time, and a 70% reduction in manual finishing, with the same raw material cost. Overall this gives a 58% cost reduction in the final moulded components.
• Weight: PFA gives a significantly improved surface finish, reducing the use of filler by 70% and reducing average component weight by 4%.
• Safety: PFA prepregs are non-toxic, non-carcinogenic and have far lower VOC emissions, eliminating health & safety concerns from the workplace.

This material has been developed directly with key companies in the aircraft interiors supply chain. The initial testing has shown that PFA composites can meet aircraft interior standards for mechanical and fire performance, whilst also providing the highlighted cost, weight and safety benefits over phenolics. Companies now want PFA prepreg to be qualified, but there are still 3 main issues to overcome before they can be accepted onto aircraft qualification test programmes. The overall objective of this project is therefore to enable significant improvements in aircraft interior part cost, component weight and worker safety compared to phenolic composites, by addressing these 3 issues:
1. Refinement: Whilst the mechanical and fire performance of PFA prepreg meets the required levels, customers are looking for refinement of the prepreg formulation to allow faster, easier processing.
2. Repeatability: The current method of impregnating the reinforcement with PFA resin does not yet provide the required high level of accuracy and consistency in the material’s properties.
3. Scale: The development has so far been undertaken on small-scale and prototype equipment which does not give the manufacturing tolerances, robustness or scale needed for secure supply.
The overall objective of this project addresses these 3 issues, to enhance the formulation, optimise the impregnation and upscale the production process of PFA prepregs, enabling the replacement of phenolic composite materials in aircraft interiors.
Both Composites Evolution and Bercella are working continuously with potential customers to ensure that the project is targeted to their requirements on performance, processability and cost. A commercialisation plan has been updated throughout the project. Key Exploitable Results have been identified and options for their protection are continuously under review.

We have tested and refined resin formulations to meet customers’ requirements on processability (tack [stickiness] of the material, resin flow, working life) and process cycle times (prepreg line speed, part cure time). This work has clearly demonstrated the most suitable resin formulation. However, work will continue at NetComposites in order to fine tune the materials for large scale production. We have also addressed the security of supply, by discussing available products, volumes and agreements with the supply chain.

Investigations have taken place to bring together the resins and reinforcement fabrics, prototyping different resin application methods, as well as the interface between the resin and the reinforcement, to achieve the required impregnation (resin weight %), final product performance (e.g. interlaminar shear strength: ILSS), surface finish and process consistency. Although the objectives have been achieved, work will continue in order to fine tune the materials for large scale production.

Work has started related to the upscaling of the production process.

Finally, the outputs of each development stage have been assessed positively against the targets for processability, performance and economics. The results have been used to steer the product development.
The results achieved so far are all inline with the expected impacts for the project. Specifically, the material being developed will enable aircraft interiors companies to use PFA prepreg materials in place of the existing phenolic materials. With this single change they will improve their economic (cheaper processing), environmental (lighter parts, bio-sourced material) and social (safer working practices) performance as part of a truly sustainable business improvement. The technical work (identification of suitable resin formulation & fabric impregnation process) have all achieved their objectives and we are now moving to the next stage of upscaling the process.
PFA is 100% derived from agricultural waste, providing a sustainable feedstock that does not impact on the production food crops and which competes on a purely technical basis with phenolic materials. The use of PFA prepregs will also allow component manufacturing companies to remove phenolic materials from their workplaces, removing the potential of worker exposure to the toxic and carcinogenic chemicals used in phenolics.
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