The outstanding performance of conventional thermosets arising from their covalently cross-linked networks directly results in a limited recyclability. The available commercial or close-to-commercial techniques facing this challenge can be divided into mechanical, thermal, and chemical processing. However, these methods typically require a high energy input and do not take the recycling of the thermoset matrix itself into account. Rather, they focus on retrieving the more valuable fibers, fillers, or substrates. To increase the circularity of thermoset products, many academic studies report potential solutions which require a reduced energy input by using degradable linkages or dynamic covalent bonds. However, the majority of these studies have limited potential for industrial implementation. This review aims to bridge the gap between the industrial and academic developments by focusing on those which are most relevant from a technological, sustainable and economic point of view. An overview is given of currently used approaches for the recycling of thermoset materials, the development of novel inherently recyclable thermosets and examples of possible applications that could reach the market in the near future.
The mechanical properties of mechanically recycled polyethylene (rPE) were studied in relation to the composition of the feedstock. This composition varied in six steps from only bottle bodies from a single type of high‐density polyethylene (HDPE) to the complete composition of an industrially sorted polyethylene (PE) product, including other packaging components, other PE‐based packages, sorting faults and residual waste. The rPE with the highest impact resistance was made from the single‐grade bottle bodies. The addition of bodies made from other types of PE already reduced the impact resistance with 11%. All the other stepwise additions of packaging components and faultily sorted objects caused the impact resistance to decrease further. Conversely, the elongation at break grew with the stepwise addition of these packaging components and faultily sorted objects. From the used methods, the best analysis method to accurately determine the polymeric composition of the rPE was found to be near‐infrared‐assisted flake analysis. This method can not only be used to determine the polymeric composition, but due to the strong correlation with the impact resistance, it is also a valuable indicator for the expected mechanical properties of rPE.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.