Corrosion resistance of alkoxysilane modified bisphenol A-epoxide coatings
Bisphenol A (BPA) epoxy was modified with amine functionalised silane (ASE) and isocyanate functionalised silane (ISE), and the modified epoxides were blended with both tetraethyl orthosilicate oligomers (TEOS oligomers) and titanium dioxide (TiO2).
These hybrid networks were characterised by solid state 29Si-NMR, contact angle, crosslink density, pull-off adhesions, and crosshatch adhesion. Corrosion resistance was examined with a salt spray test, a filiform test and electrochemical impedance spectroscopy (EIS). Modified epoxides with addition of TEOS oligomer and TiO2 fillers showed improvement in mechanical properties. The broader degree of cross-linkage was observed in ISE based coatings. In contrast, ASE based coatings had a more uniform crosslink distribution and higher crosslink density.
ASE with good barrier protection under long-term immersion conditions
The addition of TiO2 fillers increase the percolation root of ISE epoxide, but was eliminated after blending with TEOS oligomer. With TEOS oligomer addition, crosslinked ISE showed complete condensation and high pull-off adhesion (153 lb/in2). The more homogeneous and higher crosslinked polymer matrix of ASE resulted in a higher diffusion resistance, and as a consequence exhibits good barrier protection under long term immersion conditions compared with the lower cross-linked ISE epoxide.
The study is published in: Progress in Organic Coatings Volume 134, September 2019, Pages 209-218.
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