Patent ID: 7582721
Filing Date: 2009-09-01
Classification: C08G

Abstract:
1. In a process for preparing a random copolyoxadiazole from a mixture containing oleum, hydrazine sulfate, terephthalic acid, and para-oriented aromatic diacid; wherein the improvement comprises oleum addition in more than one step, comprising: (a) combining hydrazine sulfate, terepthalic acid and para-oriented aromatic diacid, (b) adding to (a) oleum in an amount not greater than 3 molar equivalent of sulfur trioxide based on moles of hydrazine with temperature of the oleum controlled to not greater than 50 degrees Celsius until dissolution occurs of oleum, hydrazine sulfate, terephthalic acid, and para-oriented aromatic diacid followed by heating in a range of 100 to 150 degrees Celsius with stirring until viscosity plateaus, (c) adding a further amount of oleum to complete the reaction to prepare the random copolyoxadiazole.