Patent Title: POLYURETHANE ELASTOMERS
Number/Link: WO 97/21750
Applicant/Assignee: ICI
Publication date: 19-06-1997
“Gist”: A polar polyether softblock and highly symmertrical hardblock results in a near-perfect polymer morphology.
Why it is interesting: ICI’s “perfect PU elastomer” is accomplished by reacting a polar, low-reactive polyether triol (75% EO random, 42 OHv) and a ‘stacking’ chain extender (MEG) with a symmetrical diisocyanate (4,4′ MDI). Some water can be added to a density of about 400 kg/m³. This combination results in a remarkable polymer morphology with a ‘nano’ phase-separated hard domain and a very ‘clean’ soft phase, resulting in a very high (>1) and symmetrical damping peak (tan δ) and an incredibly flat storage modulus (E’) up to about 200°C. Damping at positive temperatures is virtually zero, resulting in a very high resilience. The patent actually claims the shape of the DMTA trace rather than the composition of the polymer.
The elastomer is not completely “perfect” in that it has relatively low mechanical properties, such that it is perferably used in a structural- or fiber/particle reinforced composite.
1Hz DMTA trace of ICI’s “perfect elastomer”.
