Molecular composites aerospace industry

The PMR range of resin materials utilize a two-step reaction, in which a norbornene-terminated prepolymer is formed in situ by the condensation reaction of low molecule weight diamines with norbornene-capped imides or acid esters [37]. The PMR-15 designation refers to polymerization of monomeric reactants, with a mixture of diaminodiphenylmethane and a dimethyl ester and a norbornene-containing monomethyl ester, to form a condensation prepolymer having molecular weight approximately equal to 1500. PMR resins are used as matrix materials in high performance composites in the aerospace industry. 

Specialty polymers achieve very high performance and find limited but critical use in aerospace composites, in electronic industries, as membranes for gas and liquid separations, as fire-retardant textile fabrics for firefighters and race-car drivers, and for biomedical applications (as sutures and surgical implants). The most important class of specialty plastics is polyimides. Other specialty polymers include polyetherimide, poly(amide-imide), polybismaleimides, ionic polymers, polyphosphazenes, poly(aryl ether ketones), polyarylates and related aromatic polyesters, and ultrahigh-molecular-weight polyethylene (Fig. 14.9). 

Joining and adhesive properties of polymeric composites are of critical importance for emerging applications in the aeronautical, aerospace and marine industries. Traditional macroscopic adhesion testing techniques evaluate macroscopic properties of materials, with limited information on the molecular level processes that control actual performance. Nanomechanical and nanotack evaluations utilizing advanced nanoprobe techniques of polymer/fiber composites reveal differences in performance at the molecular level. 

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