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| PATENT EXAMPLES |
A sebacic acid prepolymer was prepared by refluxing 60 grams of sebacic acid with 250 ml of acidic anhydride under nitrogen for 90 minutes. The excess acetic anhydride was evaporated from the prepolymer which was then recrystallized from toluene. The crystals were then filtered and recrystallized in a mixture of petroleum ether and anhydrous diethyl ether. The white crystals were then separated by filtration and dried under vacuum. A phenylenedipropionic prepolymer was prepared by adding 60 grams of phenylenedipropionic acid to 500 ml boiling acidic anhydride under dry argon and refluxed for 60 minutes. The excess acetic anhydride is removed by an evaporator at 60 degrees C. to yield a white solid which was recrystallized from 30 ml toluene at 0 degrees C. The crystals are then extracted with 200 ml of a diethyl ether and petroleum ether (1:1) mixture for five hours at room temperature. The pure crystals are dried under vacuum under calcium chloride to yield 61 grams of prepolymer with a melting point of 74 to 75 degrees C. EXAMPLE VII A 50:50 copolymer of PDP:SA was prepared by mixing 1.14 grams of PDP prepolymer with 1.0 grams of SA prepolymer and polymerizing at 180 degrees C. under high vacuum (less than 10.sup.-2 mm Hg) for 90 minutes. The purified copolymer had a melting point of 75 to 77 degrees C., a weight average molecular weight of 58,900 and an intrinsic viscosity of 0.64 dl/g and a composition of PDP:SA (49:51 ). |
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