DMA - Peak in the Storage Modulus Curve?

[mta02hm]

Hi all,

My understanding of the storage modulus is it gradually drops off as the sample is heated due to increasing molecular motions within the material, the main chain movements being seen at the glass transition temperature. I just ran a polyurethane sample and there is a peak in the storage modulus curve, why would this be? Is it possible the reaction is continuing, resulting in a higher modulus due to the nature of the DMA test, or is there some kind of strain hardening affect occurring?

Any thoughts greatly received.

Helen

 

[Demon3]

Probably curing. Redo the measurement on the sample and see if it looks the same as the first one.


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