Effect of resins on the salt spray resistance and wet adhesion of two component waterborne polyurethane coating

Abstract

Effects of the type, chemical structure and NCO/OH of resins on wet adhesion and salt spray resistance of two component waterborne polyurethane coating were studied in this paper. The content of functional groups in resins and films were analysed by areas of their FT-IR absorption peak to study the relationship with anticorrosive performance of coatings. Coatings based on resins with more -OH tend to have stronger wet adhesion and salt spray resistance because resins with more -OH have more possibilities to react with -NCO to form a compact film with a higher crosslinking degree. The wet adhesion of coatings after 8 h of immersion deteriorated from level 1 to level 5 with the increase of NCO/OH due to the decrease of -OH in coatings to link with substrates. And excess -NCO tend to react with H 2 O to generate CO 2 to form cracked physical bubbles, which would weaken the wet adhesion.Abstract: Let F denote a eld and let V denote a vector space over F with nite positive a pair A, A * of diagonalizable F-linear maps on V, each of which acts on an eigenbasis f irreducible tridiagonal fashion. Such a pair is called a Leonard pair. We consider the se there exists an automorphism of the endomorphism algebra of V that swaps A and A * . Su is unique, and called the duality A ↔ A * . In the present paper we give a comprehens duality. In particular, we display an invertible F-linear map T on V such that the map X → A ↔ A * . We express T as a polynomial in A and A * . We describe how T acts on ags and 24 bases for V.

Seawater Absorption and Adhesion Properties of Hydrophobic and Superhydrophobic Thermoset Epoxy Nanocomposite Coatings

“…The coating durability of the coated steel with DGEB/PA cured in the absence and presence of modified NPs by using salt spray resistance, adhesion strength, and wettability measurements before and after seawater fog at different exposure times is shown in Figures 12 and 13. The salt spray results were evaluated by measuring the epoxy adhesion strength after seawater salt spray resistance exposure time with the appearance of rust and blisters under coatings surfaces on the steel panel, as listed in Table 3 [44]. The incorporation of 10 wt.% of the modified NPs in the cured DGEB/PA epoxy networks (not reported here for brevity) showed lower salt spray resistance with the appearance of much rust and blistering of organic coatings (bubble-like spots beneath) at exposure time lower than 500 h. These data were referred to as agglomeration of NPs to produce inhomogeneous surfaces that facilitated the diffusion of salts and water under coatings to form rust surfaces.…”

“…It is well-established that the superhydrophobic and hydrophobic coatings have WCA ≥ 150 • and above 100 up to 150 • . Moreover, the superhydrophobic coatings suffer from lower adhesion with different substrate on dry or wet adhesion [44]. The superhydrophobic coatings surfaces suffer from scratches, damages, aggressive corrosive environments, and abrasion to reduce the coating durability in practical working environments.…”

Enhanced Wetting and Adhesive Properties by Atmospheric Pressure Plasma Surface Treatment Methods and Investigation Processes on the Influencing Parameters on HIPS Polymer

“…Examples of such properties include hardness, corrosion resistance, and wear resistance [3]. Interface properties play a major role in the life of component and material pairing, as most damage processes start on the surface, and the surface is usually exposed to external damages during the different weather conditions and mechanical stresses [4,5]. Further interface property may be the wetting ability of a surface [6].…”

Self-Assembly of Amphiphilic Linear−Dendritic Carbosilane Block Surfactant for Waterborne Polyurethane Coating

“…For example, rail transit vehicles use high-speed electric multiple unit (EMU) coatings, which need to provide protection to the vehicle’s body for a long period of time due to abrasion caused by sand, dust, air, etc. [ 16 , 17 ]. Therefore, the standard coating thickness of polyurethane for high-speed EMU needs to reach 60–80 μm, while in some areas, because of repeated spraying, it reaches values >1.5 times that of the standard film thickness, which increases the dry film thickness to more than 100 μm [ 18 , 19 ].…”