Kryo-PU

What is this project about?
Many modern applications in the fields of aerospace, medicine and hydrogen technology now involve the use of materials at very low temperatures (cryogenic, from/below -150 °C). At these temperatures, plastics become more brittle: they break more easily and are less resistant to deformation and impact. This becomes particularly critical when an adhesive comes into contact with another material: both deform differently under thermal stress, which – especially at very low temperatures – means that internal stresses can no longer be balanced out: the bonded joint is weakened or even destroyed. Here, new mechanisms are needed at the molecular level to keep the plastic or the adhesive functional even under these extreme conditions.

What motivated you to participate in this call for proposals? Where did the idea come from?
To date, there has been a lack of fundamental, systematic research into plastics in the cryogenic field or into adhesive bonds (based on polyurethane (PU)), and there is still no generally accepted method for specifically adapting plastics for adhesive bonds so that they withstand cryogenic conditions better. At the same time, bonding is becoming an increasingly important joining technique. This led to the idea of investigating PU-based adhesive joints for aluminium profiles in the cryogenic sector, understanding failure mechanisms, and making the adhesive joint more resistant using chemical methods.

What benefits does this project bring to society and/or in terms of sustainability?
Chemistry provides materials for our modern world and optimises them to meet specific, necessary property profiles. Optimised materials are key to many sustainable innovations. The project will provide far-reaching insights into influencing polymer behaviour (using PU as an example) in the cryogenic temperature range: various chemical bonding motifs will be specifically incorporated into the polymer, and the effects on the behaviour of the adhesive formulation in terms of adhesion and cohesion will be investigated. In addition to the fundamental findings, the project will already contribute to improving the formulation of adhesive bonds for cryogenic applications.

Who else is joining in?
The project is a joint venture with the ISF – Institute for Welding and Joining Technology (RWTH Aachen). Whilst the chemical part of the project was designed and is being carried out by the IAP, the ISF is dealing with all aspects of bonding the joined parts and their characterisation. We are very much looking forward to this interdisciplinary collaboration.