Investigating the surface properties of polyurethane based anti-graffiti coatings against UV exposure

A permanent anti‐graffiti coating based on a polyurethane resin was prepared by incorporating different levels of an OH‐functional silicone modified polyacrylate additive. Static contact angle measurements and dynamic mechanical thermal analysis (DMTA) were employed to evaluate surface free energy a...

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Bibliographic Details
Published in:Journal of applied polymer science 2012-05, Vol.124 (4), p.3082-3091
Main Authors: Rabea, A. Mohammad, Mirabedini, S. M., Mohseni, M.
Format: Article
Language:English
Subjects:
ageing
Applied sciences
degradation
Exact sciences and technology
Forms of application and semi-finished materials
Materials science
Polymer industry, paints, wood
Polymers
polyurethanes
Sheets and films
silicones
surface modification
Technology of polymers
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Summary:A permanent anti‐graffiti coating based on a polyurethane resin was prepared by incorporating different levels of an OH‐functional silicone modified polyacrylate additive. Static contact angle measurements and dynamic mechanical thermal analysis (DMTA) were employed to evaluate surface free energy and mechanical properties of the coating specimens, respectively. Effect of ageing condition on the graffiti properties of the coating samples was evaluated utilizing an accelerated weathering test. Color changes, surface morphology, and variations in the mechanical properties were also examined prior to and after being exposed to UV irradiation for 864 h in a QUV chamber. Results showed that surface free energy of the samples decreased with replacement of polyol with additive up to 5 mol %. A Scanning electron microscope equipped with energy dispersive X‐ray detector revealed that for the samples containing more than 5 mol % additive, there was an enrichment of silicone at the interface of films and air. At long exposure times and higher concentrations of additive, depreciation of graffiti properties was seen. DMTA and attenuated total reflectance‐fourier transform infra‐red studies before and after ageing showed that the silicone additive tended to degrade while it could cause an increase in crosslinking density. Water contact angles and atomic force microscopy images after ageing revealed that the cause of the depletion in anti‐graffiti properties was attributed to the deterioration of the silicone additive. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
ISSN:0021-8995
1097-4628
DOI:10.1002/app.35344