Novel high performance polymeric composite materials for additive manufacturing of multifunctional components

The aim of this proposal is to develop novel high performance, nanocomposite feed materials for Additive Manufacturing (AM). The field of AM, also known also as 3D Printing, has expanded significantly over the last couple of decades across virtually all-industrial sectors due a number of key advantages that traditional manufacturing just cannot offer. These include mass customisation, geometrical complexity, tool-less manufacture and sustainable manufacturing. Among the companies using AM are GE (medical devices, and home appliance parts), Lockheed Martin and Boeing (aerospace and defense), Invisalign (dental devices) and LUXeXcel (lenses for light-emitting diodes, or LEDs). The worldwide revenue from 3D printing is expected to grow from $3.07 billion in 2013 to $12.8 billion by 2018, and exceed $21 billion by 2020, and has a potential of generating an economic impact of $230 billion to $550 billion per year by 2025.

While the forecast for AM products is huge this will only be achieved if we can actually manufacture parts with the desired properties. The majority of polymeric AM research is however focused on low glass transition temperature (Tg) polymers such as Polyamide 11, 12 , Polycarbonate and Poly Lactic acid (PLA), due to their good processing characteristics (rheological, thermal and crystallization). For advanced, high value applications in aerospace, telecommunication and defense where harsh environmental conditions often exist (and in some key biomedical application) these low Tg polymers for AM are not acceptable so there is a real need to develop materials for these applications. Whilst a sufficiently high Tg polymer could offer the required high performance, nanocomposites with increased functionalities and potential combinations of properties such as high stiffness, strength, wear and specific thermal, electrical and microwave response can really transform the performance of AM components. The ability to manipulate other properties, such as rheological and thermal performance, by the addition of nanoparticles offers further potential advantages in terms of processing characteristics.

This proposal will examine the potential of inorganic fullerene-like (IF) tungsten disulfide (WS2) or IF-WS2 as nanofillers for high value, PAEK (Poly Aryl Ether Ketone) based products made via the AM processes of Selective Laser Sintering (SLS) and Fused Deposition Modelling (FDM). The incorporation of IF particles has been shown to be efficient for improving thermal, mechanical and tribological properties of various thermoplastic polymers, such as polypropylene, nylon-6, poly(phenylene sulfide), poly(ether ether ketone). These nanocomposites were fabricated by simple melt-processing routes without the need for modifiers or surfactants . IF-WS2 have been proven to exhibit extremely high tribological performance in composites to reduce wear and coefficient of friction .These characteristics will also have important processability benefits for AM processes as will their dispersion characteristics which are superior to 1D and 2D nanoparticles. They are also the best shock absorbing cage structures known to mankind. Importantly, they are non-toxic, and thermally stable.

We will examine the two main AM processes for producing parts with engineering properties, Selective Laser Sintering (SLS) in which a laser is used to melt and sinter powdered polymer into the final part and Fused Deposition Modelling (FDM) in which a polymer filament is melted in a heated nozzle and deposited in the required pattern to form the part.

The following new knowledge will be generated: knowledge of (i) the material modifications and processing techniques required to make high performance PAEK nanocomposite materials (ii) the processes required to produce high performance materials for the additive manufacturing process of selective laser sintering and fused deposition modelling (iii) the additive manufacturing processing conditions required to manufacture demonstrator parts for an aerospace application

People: In addition to the standard academic training delivered in PDRA/PhD posts the PDRAs and PhD students involved in this project will develop skills in polymer nanocomposite development, processing and characterisation. They will gain an understanding of the industrial requirements for additive manufacturing materials and how processing influences part properties. They will also gain an understanding of the stringent requirements placed on product performance for the aerospace sector. Through the dissemination and outreach activities in the proposal they will improve communication skills and increase personal networks. Secondary school students will benefit from the proposed outreach activities. Additive manufacturing provides an exciting and interesting topic for promoting STEM. The applications envisaged in this proposal in the aerospace and biomedical sectors should also prove to be attractive to the students and help further engage them with STEM and with industry.

Society will benefit through (i) the ability to replace metal parts with lighter polymer nanocomposite parts in aerospace and other transport applications (ii) the potential of these new materials to reduce wear in biomedical implants such as hip joints (iii) better product design enabled by the additive manufacturing of complex products in high performance materials

The economy will benefit via the availability of a new range of high performance materials for the additive manufacturing industry. Aerospace and biomedical sectors requiring better performing, lightweight, multifunctional materials in relatively small quantities or in customised designs will also benefit. The worldwide revenue from additive manufacturing is expected to grow from $3.07 billion in 2013 to $12.8 billion by 2018, and to exceed $21 billion by 2020. These new materials will contribute to this projected growth.