RUBBER PHYSICAL TESTING

[GerardoS]

Hello community!
I have always wondered how confident we can be when it comes to analysing results from physical testing i.e. tensile strength, elongation, modulus, etc etc. How reliable are these results?? I always have the concern of imperfections with test pieces. Can anyone give me some advice on this matter?? If there is some literature or any web-site, it would be great, I have searched without any success. Thank you very much.
Gerardo

 

[berti]

Hi GerardoS,

there is IMHO no special procedure for rubber testing. You can apply scientific statistics to rubber testing as to any analysis.
So: Prepare many ( more then usual)testpieces from same compound, measure e.g. tensile, elongation, modulus..., calculate median and standard deviation by EXCEL or your pocket calculator. There are some statistic methods to extract values which are not "in distribution", e.g. eliminate a suspect value, calculate new x+/- 3s without it, drop, if it outside of this range (which happens often in tensile testing by imperfections like bubbles in the testpiece)

There are standards as German DIN giving values for relative deviation of methods, sometimes there are results of inter-laboratory testing published.

HTH Berti