Influence of radical photoinitiator content on UV curing process
Hybrid sol–gel coatings are widely used as protective layers for aluminum alloys because of their barrier abilities. The study aims at explaining the barrier properties of a sol–gel coating based on alkyltrimethoxysilane and methacrylate resin by its film structure. This approach was examined by modifying one photopolymerisation parameter, e.g., by varying the content of radical photoinitiator.
Results revealed that formulations containing between 3 and 9 wt% of radical photoinitiator exhibit the maximal conversion of methacrylate functions and, at a microscopic scale, a homogeneous coating where the two organic and inorganic networks are well interpenetrated.
This hybrid sol–gel microstructure corresponds to the highest glass transition temperature and the highest mechanical characteristics (elastic modulus, E and hardness, H) and the highest protection performance. This results in the best barrier properties, and thus the highest corrosion resistance.
The study has been published in Journal of Coatings Technology and Research Vol. 17, Issue 2.
Image source: Pixabay.
An overview on state of the art radical photoinitiators was published in European Coatings Journal 9/2016. The overview is available online at European Coatings 360°.