First of all thank you for this integrated forum on composite materials. Your intrinsic objective to combine mechanical, chemical and permeation knowledge in order to predict service life of plastic based materials is probably the one and only proper approach for long term analysis and quantification of composite ageing and fatigue phenomena in industrial applications.

My question is not so difficult. However, since I have not found the answer so far, it probably requires some sort of integrated frp material approach.

I have a glass fibre and/or carbon fibre epoxy composite which is exposed to Glycols, think of Ethylene Glycol or Propylene Glycol (Antifreeze, Aerospace Application). I want to know how long a composite with a chemical resistance layer of approx 3 mm, and 35 vol% fibre reinforcement inside, can be exposed to Antifreeze without delamination failure / stresses. The composite is under circumferential stress (max 0.1%).

I am specifically interested in the restrain energy that is transmitted by fibre and sizings, if the epoxy matrix swells by Propylene Glycol, in the application. Will the shear stress of the swollen matrix (say 3 vol%) exceed the interfacial strength of fibre - sizings - matrix? Is there some sort of critical swelling stress for different kinds / directions of glass / fibre / polyimide reinforced composites?

My impression is that the concept of Interlaminar Shear Stress (ILSS) is useless in these kinds of slow chemically driven ageing processes (the problem is that every literature / paper that deals with the above mentioned subject ends with ILSS figures, without solving the underlying problem, this is rather frustrating… )

Thanks,
Arthur