Effect of structure on the thermal behaviour of bisitaconimide resins - Polyimides and Other High Temperature Polymers - page 163

Effect of structure on the thermal behaviour of
bisitaconimide resins
INDRA K. VARMA ∗
Centre for Polymer Science and Engineering, Indian Institute of Technology, Delhi, Hauz Khas,
New Delhi-110016, India
Abstract—Many addition polyimides such as bismaleimides and bisnadimides have been exten-
sively investigated in the past. These resins are currently being used as matrix resins for advanced
fibre-reinforced composite materials, which find applications in the aerospace, defence and electron-
ics industries. As one of the thermoset materials, these polymers offer superior thermal oxidative
stability and better retention of properties in hot wet environments than the conventional epoxy resins.
The potential of bisitaconimide resins which cure at lower temperatures than bismaleimide or
bisnadimide resins and yield a cross-linked network with thermal stability comparable to other types
of addition polyimides has not been fully explored. In this paper, recent studies on the synthesis and
characterisation of novel itaconimide resins are described. The effect of structure on thermal behav-
iour is discussed.
Keywords : Bisitaconimide; biscitraconimide; isomerisation; thermosetting polyimides; char yield.
1. INTRODUCTION
Addition polyimides, such as 5-norbornene-2, 3-dicarboximide (nadimide),
maleimide, or ethynyl-terminated imide resins, are a leading class of thermoset-
ting polyimides. Since the early 1970's these resins have been extensively inves-
tigated as matrix resins for advanced fiber-reinforced composites, adhesives and
in multilayer circuit boards in the electronic industry [1].
Although extensive studies have been reported on nadimide and maleimide res-
ins, very few papers have been published on imide derivatives of itaconic anhy-
dride [2]. This may be due to higher material cost as well as due to some side re-
actions during their synthesis (such as isomerisation to citraconimides). However,
there are some advantages of bisitaconimides. Nadimides and maleimides are
prepared from anhydrides based on petrochemicals whereas itaconic acid is ob-
tained from easily renewable resources such as corn starch by fermentation proc-
esses using Aspergillus itaconicus or Aspergillus terreus fungi [3]. The dwindling
petrochemical feedstocks have necessitated the need to focus attention on devel-