Reduction of Air Inclusions in Sealant

Sealants are supposed to “seal”, but that core quality can be compromised if air bubbles form during the curing process. LINX investigates the impact of preparation on bubble sizes and their distribution.

Sealant is made from polymers, i.e. big, chain-like molecules. When applied, the polymers are liquid, flowing in between one another; but in the curing process they entangle and solidify, forming a vast and dense network which is a strong barrier against the ingression of water, air/gasses, etc. However, some sealants have a tendency towards bubble formation while curing, due to gas evolved by the chemical reactions going of the process. Such bubbles compromise the material in every way – by making it weaker, somewhat brittle and (above all) much more permeable to all the things that the sealant was supposed to seal against.

Understanding the numbers of bubble formation – how they grow, where and to what size – is a great asset in developing optimum curing processes. In this project, LINX explores “3D maps” of bubbles trapped in cured sealants by means of X-Ray imaging, the core expertise of DTU. By getting the maps accurate, and linking them to particular curing criteria, the involved LINX member companies attempt to strike a path towards more stable seals and (hence) better, more stable products with a longer service life.

Techniques and Methods

This focus project is started in second half of 2018 as a result of feasibility studies done by DTU and VELUX during second half of 2017 and start of 2018. This feasibility study showed the possibilities in studying air inclusions in sealant and the planning of the focus project started. The air with the focus project was to develop a method which will allow a parameter study to understand the behaviour and structure of air inclusions as a result of material and production parameters.

The first small batch of samples have been investigated and data used to develop two different approached to get statistics on the number, sizes and position of the air inclusions, one of these approached is based on machine learning. Most of the work in the focus project is planned for 2019.

Project Information

Participants: VELUX, Technical University of Denmark.
Start date, end date:
July 2018 – present
Structural analysis and reduction of air inclusions in sealant (FP08.006, Materials at operating and processing conditions).