Innovation in aerospace technologies is moving forward with a very high pace. Since the mid-1990s we have seen the birth of much more energy efficient propulsion systems, increased use of advanced materials like carbon fiber, a higher level of adhesives used and improved customer experience through noise reduction. So what’s next on the agenda for all the companies involved? Can we continue to improve the materials or have we started to reach the end of optimization? And are there any new materials coming that could be part of changing the game yet again?
Innovation in Aerospace
Royal academy of Engineering published a very interesting report in 2016, discussing the initiatives taking place within the different fields of aerospace engineering. The innovation in software systems are clearly on the rise. The communication between the aircraft and the ground, the communications between aircrafts, and data handling is being mentioned as key areas of development. Around 50% of all costs related to an aircraft is dedicated to software systems or data these days. The latter 50% is linked to the actual material costs of the aircraft. The demand for smart materials in the new age of Internet of Things (IoT) is really starting to set the pace. So material experts need to start searching for components which can help them innovate within this field. Summing up briefly what I am seeing, there is in my view three main focus areas when it comes to material innovation in aerospace industry:
- Efficiency (fuel and emissions)
- Noise (customer feel and working environment + exterior environment)
- Composites – lightweighting/strength and smart composites
The Royal Academy of Engineering states that it is down to environmental impact, fuel efficiency and cost. Now, can we foresee the microfibrillated cellulose (MFC) making its entry into this context? Well, there is little work done yet, but let’s take look at some interesting functionalities that could boost our thought process. I will further in this post circle my focus around its ability to provide strength and incorporation of sensors, making the composites smarter.
The multifunctionality of MFC and its relation to smart composites in aerospace
Microfibrillated cellulose can show for very high strength. In some studies where the MFC has been incorporated to PLA (polylactic acid), the strength was tripled. The strength at break performance from MFC is looking interesting, with data being reported to show up to 200 MPa for neat MFC films. I clearly feel the importance to state that you need to remember that strength properties from MFC relates heavily back to the product quality. By increasing the surface area of the fibrils the ability from the MFC to contribute with build strong composite is definitely an opportunity. A lot of work has been conducted within the field of strength and nanocellulose, including the 2014 article by Josefsson, Berhold and Gamsted. They claim the axial Young’s Modulus to be at 65 GPa, almost twice that of Microcrystalline Cellulose. Clearly, there is potential for engineered, lightweight MFC composites for aerospace industry.
In addition to strength, the ability to incorporate sensors into the composites is an integral part of the IoT future. There has been reports discussing the ability to prepare films (both clear films and opaque films). Meggitt, a UK based composites and polymer company, states that one of their goals is to incorporate sensors into the composites to make the composites “smart”. Like other advanced fiber structures, the nanocellulose and microfibrillated cellulose has a very low diameter of its fibers, providing the space to embed so called Fibre Bragg grating (FBG) sensors (which measures internal strain measurements). Utilizing this technology, you are able to retrieve data to identify damage on the material in the proximity of the sensor.
Sado et al. also found in their study on MFC films that they are highly thermally stable (the thermal expansion of cellulose has been measured to be as low 0.1 ppm/K) and thus can provide a sufficient performing composite entrapping the sensors. Thus, the nanocellulose and MFC may give a new alternative to composite structure.
So will nanocellulose and microfibrillated cellulose make its way into the aerospace industry going forward? Looking at the examples above, I firmly believe so.