Investigating curing-induced internal stress in epoxy coatings

A recent article describes the effects of epoxy binder, curing agent, filler, initial solvent concentration, curing temperature, and relative humidity, on the curing-induced internal stress in epoxy coatings.

According to the report, curing-induced internal stresses in epoxy coatings are highly influenced by the type and concentration of their ingredients, and the conditions applied. In this new work, the effects on the internal stress development of the epoxy/crosslinker chemistry, curing temperature, relative humidity, filler conditions, and initial solvent concentration, were studied. An elevated curing temperature (35 or 45 °C) resulted in a smaller elastic modulus and, despite an accelerated curing reaction and a higher final reactant conversion, only a slight increase, around 0.2 MPa, in the average internal stress. An increased relative humidity (from 35 to 60 %), also resulted in a smaller elastic modulus and less volumetric shrinkage and internal stress. However, at 90 % relative humidity, the internal stress, due to an enhanced final reactant conversion, was higher than observed at 60 % RH.

The study noted that the presence of either BaSO4 or CaCO3 filler in the formulation reduced the final reactant conversion and volumetric shrinkage, but resulted in a higher elastic modulus and internal stress. 0.6 MPa.

The study presents guidelines to optimise coating formulations and curing conditions to avoid internal stress.

The study was published in Progress in Organic Coatings, Volume 173, December 2022.

Follow us on social media

General Enquiries

Institute of Corrosion
Corrosion House
5 St Peters Gardens

tel: + 44 (0)1604 438222

Related News

Standards Up-date ISO

The following documents have obtained substantial support during the past two months, and have been submitted to the ISO member bodies for voting, or formal approval. ISO/FDIS 4624 Paints and varnishes — Pull-off test for adhesion (Revision of 2016 standard) ISO/DIS...