Accuracy in locating glass transitions: aging and gamma sterilization of vulcanized thermoplastic elastomers
نویسندگان
چکیده
We have studied nine thermoplastic vulcanizate elastomers (TPVs) in four series: as made, after accelerated aging, after γ irradiation, after both irradiation and aging. The materials exhibit two glass transitions, one seen in crosslinked regions and the other in un-crosslinked amorphous regions. Three techniques of determination of glass transitions have been used and the results compared, all three based on dynamic mechanical analysis (DMA): as a peak in the loss modulus E’’; as a peak in tan δ; and as the midpoint of the rapid decrease in the storage modulus E’. We recommend the last method for both fundamental and practical reasons.
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