Monomer reactants - polyimide resin

Bis-maleimide resins composed of BMI and diamines have been reported in the early 1960s in the patent literature. Since that time, a number of patents have appeared describing improvements in their properties and uses [3]. Although many bis-maleimide resins are commercially developed, relatively few reports of their use as adhesives are to be found in scientific journals [4-10]. Improvements of maleimide resins are mirrored in the improvements of thermosetting polyimides. For example, the method of in situ polymerization of monomer reactants (PMR method) was developed [6]. 

Structural modifications were envisioned early to overcome these limitations. A first improvement was outlined by preparing copolymers, which were soluble in the state of full imidation, mainly poly(ester-imide)s and poly(amide-imide)s [2,4, 5]. As an alternative to these conventional copolymers, addition polyimides were developed in the 1970s as a new class of thermosetting materials. Thus, bismaleimides, bisnadimides, and end-capped thermocurable polyimides were successfully developed and marketed [6,7]. These resins were the precursors of the modern PMR (polymeric monomer reactants) formulations [8]. 

With respect to the effect of environments, carbon fibres can be largely considered to be inert since they are stable to higher temperatures than the resin matrices can withstand. At temperatures above 300 °C, the fibres begin to degrade in oxidising atmospheres, but most polymers have a lower maximum service temperature. The advanced polyimides and PMR (polymerisation of monomer reactants) systems can survive temperatures up to 450 °C, but these are usually in short-term applications [27]. It is also unlikely that composites will be in contact with damaging solvents such as concentrated oxidising acids such as sulphuric and/or nitric acids. 

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