| 摘要 |
Fibre forming polyurea elastomers consist of structural units <FORM:1091727/C3/1> Ar is phenylene, alkyl phenylene, biphenylene or alkylene biphenyl; R is a C2-C10 alkylene radical, X is hydrogen or C1-C5 alkyl radical; m, n and y are integers and G is a divalent radical selected from <FORM:1091727/C3/2> or <FORM:1091727/C3/3> R1 is a divalent C2-C20 organic radical. The polymers are prepared by reacting a poly (oxyalkylene) diamine having M.W. 600-5000 and m.p. < 60 DEG C. have the formula <FORM:1091727/C3/4> with an aromatic diisocyanate (especially toluene 2,4-diisocyanate) to form a diisocyanate "capped" prepolymer; the latter is reacted with a diamine <FORM:1091727/C3/5> or <FORM:1091727/C3/6> to give the elastomeric polurea. R, R1 and X have the meanings defined above. The molar ratio of aromatic diisocyanate to poly (oxyalkylene) diamine may be from 3:1 to 1.5:1. In an example 2 moles of 2,4 toluene diisocyanate are reacted with 1 mole of poly (oxypropylene) diamine. The chain extender which is used in equivalent amount to the poly (oxypropylene) diamine being 2,5-dimethylpiperazine. The reaction takes place in a dimethylformamide solution.
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