CURING PARAMETERS FOR SOLVENT RESISTANCE IN EPOXY AMINE PROTECTIVE COATINGS

Abstract

This thesis investigates the protective characteristics of epoxy amine coatings from curing parameters. Using a new model formulation of Diglycidyl ether of Bisphenol F (DGEBF) and Meta-xylylenediamine (MXDA), it looks into attributing network microstructure to properties such as water uptake and glass transition temperature (Tg). Resistance properties were tested using Dynamic Vapour Sorption (DVS), Fourier Transform Infra-Red Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC.) The environmental conditions during formulation play an important part in the end characteristics of the material, with humidity being the most crucial factor. While both CO2 and humidity are required to initiate carbamation of amines, the sole presence of humidity can impact dramatically the solvent resistance of a coating and should be limited. When curing under inert atmosphere is impossible, controlling the viscosity can be a good way to limit carbamation side reactions which offset the stoichiometry. This stoichiometry factor is key in producing a good quality coating. It dictates the crosslinking density and the rate of reaction. These dictate the final properties of the coating. Should the ratio of epoxies be greater than that of amine, a homopolymerisation agent would provide a good alternative to the missing amine groups. Though samples may experience slightly increased solvent uptake, the Tgs remained high. Excess amine however, was shown to be more detrimental to the protective properties of the polymer. Exposure to solvents showed the importance of polarity in maintaining the protective characteristics of a coating and permitted the discernment of leaching phenomena, with certain solvents being able to enter into chemical reactions with the network. As expected, solvent exposure decreased the physical properties, but recovery of these were in part 13 possible and as such was linked to the volatility of the solvent. The use of DVS also led to the discovery that rate of uptake remains unaffected with ageing and plasticisation, though overall water content does not. The rate of uptake, however, is controlled by the relative humidity around the sample.

Date of Award	31 Dec 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Stuart Lyon (Supervisor) & Stephen Edmondson (Supervisor)