| 摘要 |
<p>A method is provided for synthesizing block polymers which are thermoplastic elastomers. The thermoplastic elastomers are useful as binders in high-energy compositions, such as propellants, explosives, gasifiers or the like. The block polymers have both (A) and (B) blocks; the A blocks being crystalline at temperatures below 60 DEG C and the B blocks being amorphous at temperatures above -20 DEG C. Both the A and B blocks are polyethers formed from monomers of oxetanes and/or tetrahydrofuran. To prepare the block polymers, the (A) and (B) blocks are separately prepared and separately end-capped by reacting each block with a diisocyanate in which one of the isocyanate moieties is substantially more reactive with the terminal hydroxyl groups of the blocks than the other. Reaction of the more reactive isocyanate moiety with the terminal hydroxyl groups leaves the other isocyanate group free. The end-capped (A) and (B) blocks are mixed and reacted with a short linking compound which has two isocyanate-reactive groups.</p> |
