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[Display omitted] • Novel environment-friendly double layer powder coating modified by epoxy (PVC-PVC/EP) was prepared to improve the adhesion and corrosion resistance of the coating. • Compared with the two curing methods of double layer powder coating, the layer by layer curing method has lower porosity, stronger shielding effect and better comprehensive properties than the co-curing method. • When the amount of epoxy in the primer is 50wt%, it can effectively enhance the adhesion of the coating by forming covalent bonds with the metal surface by hydrogen bonds. • The excellent corrosion resistance of the double-layer coating is mainly due to the epoxy in the primer improves the adhesion of the coating, and the PVC in the topcoat improves the barrier of the coating. To reduce the harm of solvent based coating to the environment, a new type of composite powder coating with environmental protection and good corrosion resistance was reported. The epoxy resin modified PVC powder coating was used as a primer and pure PVC powder coating as a topcoat, which could be applied to the corrosion protection of steel in marine environment by electrostatic spraying. The structure of the coating was confirmed by SEM, FT-IR, Raman and TEM, and the effects of co-curing and layer-by-layer curing on the coating were compared. The mechanical property test, salt spray test, SEM and AFM results revealed that the material obtained the highest adhesion and salt spray resistance when the epoxy content in the primer was 50 wt%. In contrast to the pure epoxy coating and the pure PVC coating, the EP-PVC coating exhibited an excellent corrosion resistance, owning to the good adhesion of composite primer and the good barrier and corrosion resistance of the topcoat. [ABSTRACT FROM AUTHOR]

• A new cross-linked polyester with high degradation is synthesized. • The synthetic polyester can be degraded efficiently by GSH and lipase mixture. • The influence of changing the ratio of raw materials on the thermal properties and solubility of polyester is investigated systematically. • The volatility of traditional styrene crosslinking curing is overcome by the use of UV click curing. Unsaturated polyesters, in particular unsaturated polyesters with low volatility or without styrene, are gaining increasing importance in gel coatings, adhesives and molding resins. However, the cured unsaturated polyesters are usually described as non-degradable polyesters, which will lead to environmental and safety problems. In this paper, a kind of unsaturated copolyester with different binary acid composition, named poly (butylene succinate-co-butylene itaconic) (PBISx), was synthesized. Then, a photo-curable polyester(CPBIS) which can degrade under certain conditions was obtained by thiol - ene click reaction without adding styrene curing agent. The physical properties of unsaturated polyester PBISx can be effectively controlled by changing the ratio of raw materials, such as T g from - 23.7 oC to - 45.2 oC, Xc from 38% to 14%, and T m from 109.6 °C to 74.9 °C. It was found that CPBIS completely lost its degradability in lipase when its gel rate exceeded 98%. However, CPBIS could be degraded in GSH regardless of the gel rate, and lipase resumed its degradation in the GSH/lipase mixture, and the degradation rate reached 12% at 70h, attributed to the selective degradation of C-S-C bond by GSH and the secondary degradation of ester bond by lipase. [ABSTRACT FROM AUTHOR]

• A curing kinetics is reported. • Modification of waterborne polyester by a new Mercapto-based POSS. • The hydrophobicity and adhesion of polyester coatings are obviously enhanced. • It provides a theoretical basis for the modification of waterborne polyester. The research on UV curing kinetics of waterborne polyester is the basis for regulation of film formation rate. In this paper, a kind of reinforcing agent, namely polyhedral oligomeric silsesquioxanes (POSS), is adopted as modifiers to enhance hydrophobicity and adhesion of polyester coatings, and the effect of POSS on the thiol-ene UV curing kinetics including with the aspects of activation energy, reaction order and control steps are investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR). The results show that POSS is not found to significantly affect the reaction order, but change the activation energy obviously. A small amount of POSS can affect the click reaction rate of thiol-ene. The UV curing reaction rate of thiol-ene modified by POSS is mainly controlled by propagation growth rate. There is a resistance parameter in the reaction process, which can effectively control the reaction rate of thiol-ene UV curing of waterborne polyester. [ABSTRACT FROM AUTHOR]