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US 7,582,721 B2Granted
Two step preparation of random polyoxadiazole copolymer and articles resulting therefrom
AssigneeE.I. du Pont de Nemours and Company
InventorsKiu-Seung Lee, Harry Lee Smith, Jr.
Life of this patent
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Abstract
In a preparation of random polyoxadiazole copolymer by reaction of a mixture of oleum, hydrazine sulfate, terephthalic acid, and isophthalic acid, the improvement requires the addition of oleum in more than one step.
Claims13
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.
1 more element
Dependencies are inferred from the claim text.