Page 259 - Engineering Plastics Handbook

Chapter
10

Thermoplastic Polyimide (TPI)

Atsushi (Art) Morita
Mitsui Chemicals Inc.
Research and Development Center
Materials Science Laboratory
Chiba, Japan

Introduction
In the case of polyimides, aromatic polyimides polymerized from aro-
matic monomers which were insoluble and infusible had always been
present. Of all the polyimides, nonthermoplastic polyimides polymerized
from pyromellitic dianhydride (PMDA) and bis(4-aminophenyl)ether
(ODA) have a long history of roughly 40 years since commercialization
under DuPont. The polyimide cannot be melted or injection-molded and
therefore has some limitations for complicated design and productivity.
In the late 1980s, Mitsui Chemicals, Inc. [1] began investigating and
developing a thermoplastic polyimide to meet industry needs. As a result
®
of these efforts, a super engineering plastic called Aurum was launched.
This material is synthesized from pyromellitic dianhydride and 4′-bis
(3-aminophenoxy)biphenyl and has a high heat resistance with glass
®
transition temperature T = 482°F (250°C). Aurum is an injection-mold-
g
able semicrystalline polyimide, but it has a very slow crystallization rate.
The part obtained through injection molding is amorphous, not crys-
®
talline, although Aurum is a semicrystalline polymer. The postcuring
after injection molding enabled crystallization, but control of the tight
dimension was not sufficient. In the early 2000s, another new thermo-
™
plastic polyimide entered the market, called SuperAurum, an in-mold
crystallizable polyimide, which has an excellent HDT of 752°F (400°C) with

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