The polymer is widely applied in automotive and aeronautic sectors, but difficult to recycle due to complex properties
By Julliane Silveira
When the subject is recycling, people tend to think about domestic waste, especially about paper and plastic packages. And what can be done to recycle larger and more complex materials, like composites used in cars and aircraft production?
According to Boeing Company, it is expected that up to 7,200 commercial aircraft will be retired from active service in the next 20 years and all should be available for recycling.
An article published in the V8N3 edition (Jul./Sep. 2016) of JATM (Journal of Aerospace Technology and Management) presents a new aramid fiber recycling process, aiming to give new options for the reuse of some aircraft and car components.
Aramid fiber is an important polymer, applied as reinforcement in high-performance composites. This polymer is widely used in functions that demand a high-performance material in many sectors, like automotive and aeronautic. It is an important material present in components that require high strength-to-weight ratio, high strength to failure and high temperature resistance – that´s why it is commonly used in fairings, engine content rings, skins, floor panels, landing gear doors and radome.
Worldwide reports show global demand for aramid fibers will increase by an annual growth rate of 7% until 2020, reflecting the growing need for materials that contribute to enhanced safety and security, low weight and help reducing energy consumption.
Considering these facts, the development of more efficient and more ecological ways of recycling aramid fiber/neoprene is very important. However, there is a tough issue: high-performance composites are generally hard to recycle due to their properties and the difficulty in separation of components.
The study suggests a new process, showing that is possible to carry out the separation of the components from a composite material made from aramid fiber and polychloroprene polymer (neoprene) without solvent usage and less damage to the fiber.
To do so, it was used a pyrolisis oven with controlled atmosphere and CO2 injection. For the degraded separation, it was designed a mechanical washing machine. To complete the materials separation, it was used a manual cleaning process.
“The techniques used in this research are cheaper and more eco-friendly than other available recycling methods for aramid fiber”, explains Rita Sales, the lead author of the paper and researcher at Technology College of São Paulo State (FATEC). Gas waste, deriving from pyrolisis, can be properly treated and the wastewater proceeding from washing techniques might pass through a process of removing contaminants.
Recycled aramid fibers can be used as reinforcing material, being applied, for example, to reinforce concrete and floor manufacturing. The pyrolisis process, presented in the study, allows the complete decomposition of neoprene, giving a final product of easy manipulation. “Mechanical processes, commonly used for aramid fiber recycling, do not remove neoprene without damaging the fiber and give a product that is hard to handle”, says Sales.