The most reliable way to test the lifetime performance of a product, component part or material is to put it in the service environment and re-assess it after the desired service life. Such real life testing may provide good data, but in the majority of cases, the investment in time is just not feasible. In these instances, accelerated testing offers an effective solution in a much shorter time frame.
We have specialist expertise in conducting accelerated ageing test programmes, and can advise:
- Whether accelerated ageing will be viable option for your project.
- The appropriate degree of acceleration, based on material used.
Accelerated testing of plastic and rubber materials is a complex process with more uncertainty than simple physical or mechanical characterisation. Typically, the greater the acceleration process, the more likely the test is to be unrepresentative of actual ageing.
Accelerated testing is also only effective if the material under test retains its physical state and does not undergo any new physical or chemical processes as a result of the accelerant. Polymer behaviour is not straightforward and there are limitations to the accuracy of results even at low acceleration levels. Despite these caveats, accelerated testing can be highly effective.
Our experts will work with you to understand your specific requirements and design a suitable and effective test programme
Contact us to find out how an accelerated ageing programme could benefit your product development.
Accelerated Testing Services available at Smithers Rapra include:
The most common method of accelerating ageing is to increase the environmental temperature. The empirical rule that every 10°C doubles the reaction/ageing rate is a good starting point, but is very approximate. Whilst heating, significant softening and warpage may also occur; this structural change could have an influencing effect on the functional or dynamic property. The material might also pass through a transition that introduces processes that would not occur in normal service.
Light resistance is an important consideration for aesthetic as well as physical properties, but again accelerating the effects is far from straightforward. Light, unlike heat, is not a constant factor globally – the duration and intensity of light a material will see is dependent on its global location. Light exposure via accelerated weathering can be used to simulate this, but there are limitations that only experience can help to assess.
When implementing fatigue testing, major consideration needs to be given to test speed and rate. Rubber and plastics unlike metals are not fully elastic – they have a viscous behaviour element and this behaviour is sensitive to time (creep/relaxation) The long tangled polymer chains also generate heat as they move past one another. Increasing the test speed therefore only works if the polymer reacts in a representative manner and does not undergo any significant internal shear heating during the test.
For degradation guidance please get in touch with our featured expert.