Comment by Composite Analytica on 17 May 2010 at 16:07:54
Thanks for your kind feedback.
According to the most reputable models on ageing, physical ageing (including creep and free volume contraction of polymers, think of an epoxy below the glass transition) does not influence the interfacial toughness (expressed in Joule per square meter) if determined in the correct manner. This has been extracted from very rigorous experiments and modelling on fibre pull-out.
However, chemical ageing resulting in matrix plasticizing, chemical degradation of an interfacial adhesive/sizings and matrix material expansion by mass uptake and thermal, certainly influence interfacial strength. No matter whether a microscopic particles (fibres / graphite filler) or nanoscopic particles (carbon nanotubes, a.k.a. CNT's / functionalized partially oxygenated graphene sheets, a.k.a. FGS) based composite are involved. Of course the magnitude of these effects are different, also between microscopic and nanoscopic materials. Indeed check CheFEM
for a logical approach / simulation of these effects.