Today's KNOWLEDGE Share
Little attention is devoted to testing polymers at very low temperatures, like, say, at liquid nitrogen temperature.
Why would this be of any help to better understand our polymers ?
Well, because at those cryogenic temperatures Plasticity, and thus Yielding, are totally suppressed, which only leaves the door open to brittle fracture.
So what ? All polymers will be brittle when dipped in liquid nitrogen ? How's that useful ?
The stress@break at nearly -200°C will perfectly reflect the polymer resistance to "cavitation".
You will therefore be able to access the true BRITTLE STRENGTH of your polymer.
Not only will you be able to rank various plastics in that respect (as depicted), you will also gain novel insight on a very important failure criterion to be used subsequently at other temperatures as well, since this threshold is almost T independent.
source:Vito leo
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