Acid-Base and Catalytic Properties of Metal Compounds in the Preparation of Polyethylene Terephthalate)
作者:
JongShik Chung,
期刊:
Journal of Macromolecular Science: Part A - Chemistry
(Taylor Available online 1990)
卷期:
Volume 27,
issue 4
页码: 479-490
ISSN:0022-233X
年代: 1990
DOI:10.1080/00222339009349570
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Catalytic activity of a metal complex for both the transesterification of DMT (dimethyl terephthalate) and the polycondensation of BHET (bis(2-hy-droxyethyl terephthalate)) is described in terms of an acidity function formulated from the physical properties of the metal ion. Catalytic activity for both reactions is governed by the acidity of the metal ion, not by the type of anionic ligand. Maximum catalytic activity is observed with optimum bond strength between the metal ion and the double-bonded oxygen in the ester carbonyl group of DMT or BHET. Thus, a basic (less acidic) metal ion exhibits high catalytic activity for a more basic oxygen in the ester carbonyl of DMT, while a more acidic metal ions exhibits high catalytic activity for a less basic oxygen in the ester carbonyl of BHET. in the polycondensation reaction, a semiconductor metal ion shows higher activity than an insulator metal ion when compared at the same acidity value, but the former also catalyzes side reactions which can cause discoloration of the final polyethylene terephthalate) polymer. Discoloration is enhanced when a semiconductor metal ion has a redox couple during polycondensation.
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