| 摘要 |
1480072 Polyetherimides GENERAL ELECTRIC CO 29 July 1974 [3 Dec 1973] 33347/74 Heading C3R A polyetherimide of intrinsic viscosity at least 0À1 dl./g. (DMF/25‹ C.), made by reacting equimolar amounts of a dinitrobisimide and an alkali diphenoxide MO-R-OM at up to 80‹ C. in a dipolar aprotic solvent, is stabilized against gel formation at elevated temperatures by heating a solution thereof in an organic solvent and containing an alkali metal organic stabilizer R<SP>2</SP>XM to a temperature of up to 60‹ C. for a time at least sufficient to render it free of tendency to gel at temperatures up to 315‹ C. In the formulµ R<SP>2</SP> is C 1-8 alkyl or an optionally substituted C 6-20 aromatic hydrocarbon radical; X is O or S; M is Na, K or Li; R is a C 6-30 aromatic radical and R<SP>1</SP> is an up to C 20 organic radical. Reference is made to Specifications 1,392,649 and 1,480,073 in respect of the polymers and their preparation. In specific examples the stabilizer is sodium p-cresoxide, p-thiocresoxide or phenoxide. |
