Latest Technoloy for Anticorrosion Waterborne Epoxy Coatings

Issues waterborne epoxy coatings analysis –the benefit you care
 

The waterborne epoxy (WEP) coatings tend to have significant micropores and defects during the film formation, resulting in unsatisfactory long-term corrosion resistance.

Issues solution

To deal with this issue, a series of nanofillers have been added to waterborne epoxy coatings’ formulations to improve anticorrosive performance, such as clay (montmorillonite), polyaniline (PANI), graphene and hexagonal boron nitride (h-BN) . Among them,graphene is a representative two-dimensional (2D) material, which has recently attracted more and more attention due to its high thermal conductivity, high electrical conductivity and excellent barrier properties.
 However, the complex preparation process of waterdispersible graphene and the “corrosion promotion activity” of graphene caused by its high electrical conductivity make graphene less attractive.

Layered α-zirconium phosphate nanosheets (α-ZrP), having a chemical formula of Zr(HPO4)2•H2O, are a typical two-dimensional material. The layered α-ZrP can be easily exfoliated into single layer α-ZrP nanosheet using an organically strong basic amine . The exfoliated ZrP nanosheets stay very stable in water and its aspect ratio can be precisely controlled by mature synthesis methods of α-ZrP,making them a good material for the fundamental study of discotic liquid crystals in physical chemistry . Recently, studies have indicated that α-ZrP/polymer nanocomposites have excellent gas barrier properties . Therefore, the exfoliated α-ZrP are suitable as nanofiller to improve the corrosion resistance of WEP coatings by reinforcing the barrier properties to delay the penetration of corrosive mediums .

 

In this study, Tris buffer was used to exfoliate layered α-ZrP in water, obtaining a suspension of the exfoliated α-ZrP with a pH of 8.5.And then PDA monomer (dopamine hydrochloride) was directly added into the system to prepare PDA functionalized α-ZrP (f-ZrP) by situ polymerization. The nanocomposite coatings consisting of f-ZrP and WEP were prepared and applied on mild steel.

Process of exfoliation and functionalization of α-ZrP (f-ZrP) and the preparation of f-ZrP/WEP nanocomposite coatings.




  



Conclusion
 

Layered α-ZrP nanosheets were successfully exfoliated and functionalized in one pot by introducing Tris as an exfoliate agent as well as a buffer solution for PDA situ polymerization on the surface of exfoliated α-ZrP nanosheets.

The WEP nanocomposite coatings with 1.0 wt% f-ZrP exhibit an improved anticorrosion performance with Icorr of 6.60 × 10⁻⁹ A·cm⁻²after 36 days immersion in NaCl solution,which are one order of magnitude lower than that of blank WEP.

Such an anticorrosion enhancement of f-ZrP/WEP is attributed to the effective high aspect ratio after exfoliation by Tris and good compatibility with polymer after PDA functionalization.

Moreover, the introduction of PDA on the f-ZrP improves the crosslink density and adhesion of f- ZrP/WEP, which also benefit the reinforcement of anticorrosion performance.

(Contents lists available at ScienceDirect Progress in Organic Coatings)