What are the accelerating conditions usually used to give the same degradation mechanisms as in natural service for epoxy/glass laminates, especially in terms of: sampling time, final ageing time, temperature, moisture percent, ageing liquid, time for renewing liquid and also flow direction?
Ideal replication of natural degradation is not possible.
But 2 common accelerated ageing conditions are 175C dry air or 125C water autoclave.
Test conditions will depend on expected operation conditions.
simply, add chemicals you expect to encounter during normal operation..
Thanks Oleg Nizhnik. Some papers recommend a temperature of 10-15 °C below Glass transition one. In the standard ASTM D5229, it's 25°C under wet Tg.
Accelerated ageing conditions are prescribed in a variety of standards for laminated glass products, with different application scopes considered, in terms of product compositions (type of interlayer...) and in terms of configurations in use (e.g. vertical glazing, sloped glazing in buildings, windshield, etc.). Some ageing tests have been defined with regard to the assumed application scope and conditions in use, other are defined with regard to the expected sensitiveness of the laminated glass product / type of interlayer, namely to investigate the sensitiveness to identified ageing agents disregarding specific exposure conditions in use.
Among others, the EN ISO 12543-4 prescribe three types of ageing tests for assessing the durability of laminated glass products for building applications, a high temperature test (2 hours at 100°C, in principle by immersion in boiling water), a humidity test with/without condensation (2 weeks at 50°C, at 100% / 80% RH respectively), and a radiation test (2000 hours exposed to a standardized UV-radiation spectrum), all performed on specimens of determined dimensions (plates of 30x30cm).
The EOTA released a guideline on this topic, the EOTA GD 003 "Assessment of working life of products" (1999), which can be retrieved from their website www.eota.eu. This guide rather aims at giving a more general methodological framework in the context of the assessment of performances of construction products.
In summary, if you make an extensive search, you will find a relatively wide variety of ageing test conditions, corresponding to different fields of interest and assumptions. In order to select the most appropriate ones for your case, you should specify / refine your application scope and the specific goals of your experimental investigations, in my opinion.
In my thesis (http://hdl.handle.net/1854/LU-4346098) I discussed the issue in some extent (with focus on laminated glass products used in non-conventional building applications, in the European standardization framework), and made an attempt to propose a structured methodological framework for designing experimental campaigns. Yet to be challenged by peers...
http://hdl.handle.net/1854/LU-4346098
Natural service is quite vague. Is there the possibility of high solar or other radiation, high oxygen, high moisture, thermal cycles, humidity cycles, cleaning chemicals, solvents, fuels or oils contact, micro-organisms? For example, rebars in concrete constructions are exposed to alkaline environments that can be quite aggressive to the glass fibres.One of the most important thing is to identify the environment where the part will evolve.
Also, if the part is highly loaded during its environmental exposure, it can have a strong effect on the aging process. For example, load can reduce the activation energy of oxydative process in polymers and some glass fibres are sensitive to stress-corrosion.
Finally, it is good to remind that some of the aging processes have strong synergy.
I think that the following document could provide you with some guidance for you to start.
http://www.npl.co.uk/upload/pdf/depc_mpr_016.pdf