Polybismaleimide

The bismaleimide can then be polymerized by reaction with additional amine to form polyaininobismaleknide or by radiation-induced homopolymerization to form polybismaleimide (4). 

The primary resin of interest is epoxy. Carbon-fiber-epoxy composites represent about 90% of CFRP production. The attractions of epoxy resins are that they polymerize without the generation of condensation products that can cause porosity, they exhibit little volumetric shrinkage during cure which reduces internal stresses, and they are resistant to most chemical environments. Other matrix resins of interest for carbon fibers include the thermosetting phenolics, polyimides, and polybismaleimides, as well as high-temperature thermoplastics such as polyether ether ketone (PEEK), polyethersulfone (PES), and polyphenylene sulfide. 

The efficiency of the kinetic model has been demonstrated for many substrates polypropylene (2), polyethylene (3-4), poly(ethylene terephthalate) (5), polyisoprene (6), sulphur vulcanized polyisoprene (7), polybutadiene (8-9), amine crosslinked epoxy (10) and polybismaleimide (77) in large temperature, y dose rate and oxygen pressure ranges. 

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). 

Polybismaleimide (molding resin) Polybismaleimide filament winding and laminating resin Bismaleimide/epoxy adhesive Bismaleimide/ epoxy... 

Table 6.3 Effect of increasing the toughness of a brittle polybismaleimide adhesive on the single lap shear strength of steel joints [72-75].

Two basic types of polyimides are of commercial significance. In the first type, which are unmodified polyimides, imide is the principal functional group present. In the second type, which are modified polyimides, other functional groups are also present modified polyimides include poly(amide-imide)s, polyesterimides, polyetherimides and polybismaleimides. The development of this large variety of modified polyimides has been stimulated by the desire to find materials which are more readily processable than the unmodified polyimides whilst retaining the same superior properties. 

Polybismaleimides utilize an approach to polyimide synthesis which is different from that used for the polyimides described above. In the latter cases, imidization takes place after polymerization has occurred. In polybismaleimides, preformed imide groups are present in low molecular weight intermediates which are subsequently polymerized. 

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