Epoxy-amine coatings

Epoxy-amine cured coatings based on di-, tri- and tetra-functional epoxydes and aliphatic or aromatic amines (Table 4.2) undergo complicated photoreactions when exposed to UV radiation. 

At least four kinds of chromophores can contribute to the colour development during photo-oxidation of epoxy resins [216, 218-220]  

Products resulting from the oxidation of the phenoxy part. The most 

The occurrence of a photo-Fries rearrangement is well established in polycarbonates (cf. section 4.5), which contain very similar structures. 

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Two-bath, two-stage dyeing process, 9 198 Two-bladed impellers, 16 672-673 Two-color thermometers, 24 457 Two-component epoxy—amine coatings, 10 443... 

Figure 6. XPS C Is (left) and 0 Is (right) spectra of the interfacial substrate surface of epoxy-amine coating on bare steel following cathodic polarization testing (solid curves). Also shown is an approximate curve resolution for each spectrum components of the C Is spectrum are, from left, alkane, ether, and carbonate principal components of the 0 Is spectrum are, from left, iron oxide, carbonate, ether, ad adsorbed water (29.) or sodium Auger ( ). Reproduced with permission from Ref. 29. Copyright 1981, Pergamon Press.

Fig. 12.1 Schematic illustration (cross-sectional view) of epoxy-amine coating during exposure to ultraviolet (UV) radiation and humidity. After Kiil [3]...

Chemically different cross-linkers and/or differences in equivalent weights of epoxy and/or cross-linkers can result in oxidation zones of very different thicknesses. Monney et al. [9] found that for highly cross-linked epoxy-amine coatings, the stable oxidation zone, reached after 10 days, is only about 2 pm, whereas Mailhot... 

Fig. 12.2 Simulations of the effects of Xcl, max on the stable erosion rate and lag time for a highly cross-linked epoxy-amine coating using the model of [3]. Xcl, max is the degree of surface conversion of elastically effective network chains (cross-Unk density) at which erosion is initiated. The stable erosion rate is established shortly after the lag time has passed. Conditions are T=50 °C, RH=75 %, and =480 W/m (295-400 nm). Other input and model parameters are provided in the figure caption of Fig. 3 in Rul [3]...

In addition to the essential assumptions discussed above, there are other assumptions that would benefit from further investigations. These are listed in [3] and discussed for the case of epoxy-amine coatings. An example that deserves mentioning is a detailed characterization of the oxidation zone. The size and degree of penetration of cracks, the level of porosity, and the horizontal homogeneity of the surface are, in particular, issues of interest. Modem analytical tools may help to map these properties. 

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