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Chap._900004

# Chap._900004 - (b How long is the reaction Assuming kp is 2...

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Example. In a preparation of polyester by starting with stoichiometric amount of adipic acid (1M) HOOC-(CH 2 ) 4 -COOH and ethylene glycol HO-CH 2 -CH 2 -OH (1 M), the reaction is carried out under constant vacuum to remove by-product and stopped until the acid group concentration drop to 0.01 M, based on end group analysis. (a) What is the number average molecule weight of the resulting polyester?
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Unformatted text preview: (b) How long is the reaction? Assuming kp is 2 x 10-3 l/mole sec. H O-CH 2-CH 2-O-C-(CH 2 ) 4-C O-H t ~ 5 x 10 4 seconds = 13.8 hours # X n = k p [Mo] t + 1 100 = 2 x 10-3 x 1 x t + 1 = 86 x 100 + 18 = 8618 g/mole # 18 g/mole M eg = 86 g/mole M n = M st Xn + M eg M st = = 100 0.01 1 = x O O- H 2 O n HO-CH 2-CH 2-OH + n HOOC-(CH 2 ) 4-COOH = 1 1 - p X n [M o ] [M] =...
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• '10
• CHUNG,TZE-CHIANG
• 1 m, Ethylene glycol, 0.01 M, ethylene glycol HO-CH2-CH2-OH, number average molecule, acid group concentration

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