Polyurethane Elastomers with Very Low Glass Transition Temperature

Title: Low temperature segmented copolymer compositions and methods

 Number/Link: US8334356

Applicant/Assignee: Boeing

Publication date: 18-12-2012

Gist”: Polyurethane/polyurea elastomer based on a softblock mixture comprising dihydroxyalkyl terminated polydimethylsiloxane and a hydroxy terminated perfluoroether (or other low Tg softblock like OH terminated polybutadiene, polyphosphazenes etc) together with a rigid diamine chain extender (DETDA type) and a diisocyanate (HMDI in the examples). The softblocks have a molecular weight of 5000 or more and a functionality of 2.

Why it is interesting:  The materials are claimed to have a Tg between -60 and -110°C with still very high elongation and tensile strength values at -100°C. The molecules are linear but will probably not melt because of the high urea content.  They will however be soluble in the correct solvents.

Tgs

Modulus-Temperature graphs of materials according to the invention.

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