Nondestructive Inspection of Rubber
A new technique for testing the condition of rubber products could lead to cost and time savings for industry and improve safety, by making it easier to check the likely performance life of parts in service.
Scientists from CSIRO and Monash University have developed a technique that can evaluate the condition of rubber products such as conveyor belts or vehicle tyres.
The technique uses nuclear magnetic resonance (NMR) techniques, which involves putting the sample into a magnetic field to measure the "health" of the rubber. It could lead to the development of a hand held scanning device used to check components while they are in service, eliminating the need to take samples. This will mean that people will be able to get the full life out of components but replace them well before they fail.
"Unfortunately, rubber performance degrades over time due to ageing," says CSIRO's Dr Anita Hill.
"Rubber ageing results in a loss of flexibility, abrasion resistance and elasticity. For many abrasive and erosive applications (e.g. conveyor belts transporting highly abrasive materials or most passenger car tyres) degradation is not a concern because the rubber will be worn away before any significant ageing effects occur."
"However rubber degradation can lead to catastrophic failure, such as a retreaded truck tyre "blow out". In industry it can cause costly downtime and can be dangerous."
Rubber degradation has been very difficult to predict because its rate depends on many factors such as temperature, chemical environment, loading conditions and type of rubber.
"Current inspection techniques for rubber condition rely on observing the subsequent effects of ageing, for example cracks or tears in the rubber — by the time these appear it can be too late to prevent failure," says Dr Hill.
"Our new technique will give earlier warning if a rubber part such as a conveyor belt is degrading or losing elasticity, so that the part can be replaced well before failure occurs."
The research has been applied to the failure analysis of rubber conveyor belts and processing tank liners, but is equally applicable to other rubber products that are subjected to wear, such as vehicle tyres.
"NMR techniques can be used to characterise the polymers in the rubber so that over time we can detect molecular symptoms of rubber ageing, such as changes in polymer chain length, crosslinking and the presence of degradation products," says Dr Maria Forsyth of Monash University.
"From this we can get some idea of the likely performance life left in the rubber."
Dr Hill says that the next step is to adapt this technique to simpler NMR equipment which is robust, portable and can show the results in a simple way.
More information:
Dr Anita Hill, CSIRO Manufacturing Science & Technology, 03
9545 2665
Email:
anita.hill@cmst.csiro.au
Dr Maria Forsyth, Dept. Materials Engineering, Monash
University, 0419 535 811
Email:
Maria.Forsyth@eng.monash.edu.au
