Outdoor exposure and accelerated weathering of polyurethane/polysiloxane hybrid coatings

•Weathering data for Inorganic/organic hybrid Urethanes Unicoat.•Comparison of Oligoester Segment.•High Acidity Changes Degradation Mechanism. Two Polyurethane/polysiloxane hybrid coatings were compared using both real time exposure and accelerated weathering. The urethane coatings were differentiat...

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Bibliographic Details
Published in:Progress in organic coatings 2019-05, Vol.130, p.44-57
Main Authors: Gao, Tongzhai, He, Zhouying, Hihara, Lloyd H., Mehr, Hamideh Shokouhi, Soucek, Mark D.
Format: Article
Language:English
Subjects:
Accelerated tests
Carbon 13
Coatings
Cyclohexane
Dynamic mechanical analysis
Erosion
Exposure
Fourier transforms
Industrial parks
Infrared analysis
NMR
Nuclear magnetic resonance
Organic-Inorganic hybrids
Polyester resins
Polyurethane resins
Polyurethanes
Structure-property relationship
Thermosets
Urethanes
Volcanoes
Weathering
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Summary:•Weathering data for Inorganic/organic hybrid Urethanes Unicoat.•Comparison of Oligoester Segment.•High Acidity Changes Degradation Mechanism. Two Polyurethane/polysiloxane hybrid coatings were compared using both real time exposure and accelerated weathering. The urethane coatings were differentiated by oligoesters selection with one being derived from cyclohexane diacids (CHDA) and 2-butyl-2-ethyl-1,3-propanediol (BEPD) and the other adipic acid (AA), isophthalic acid (IPA), 1,6-hexanediol (HD), and trimethylol propane (TMP). Three sites in Hawaii, Campbell Industrial Park (CIP), Kilauea Volcano, and Marine Corp Base Hawaii (MCBH), were selected for the outdoor exposure test with the increasing severity of the environment. After weathering, the coatings were analyzed by Fourier transform infrared spectroscopy (FTIR) and solid state 13C nuclear magnetic resonance (NMR), Dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), and Scanning electronic microscopy (SEM). Urethanes based on cycloaliphatic oligoesters exhibited much better appearance compared to the aromatic-based polyesters. A degradation of both the carbamate and ester functionality was observed spectroscopically which was accompanied by an increase in Tg, and erosion of the surface of the coatings. It was found that the accelerated weathering test conducted in weatherometer provides harsher conditions than the three outdoor exposure tests (marine, volcano, and industrial park), while marine is the harshest among the three outdoor exposure sites.
ISSN:0300-9440
1873-331X
DOI:10.1016/j.porgcoat.2019.01.046