Condensation prepolymers polyimides

Historically, the adhesives based on reactive condensation prepolymers were the first materials to he extensively studied, developed, and introduced to the market. One of the best performing polyimides in this category is Nolimid 380, produced by Rhone-Poulenc after an extensive series of tests. The resin binder is the mixture of monomers 30a and 30b, as well as the low-molecular-weight (oligoimide) poiyimide 31 of Fig. 9.15. Typical compositions are prepared as previously reported by mixing the two monomers and 4,4 -oxybisbenzeneamine in NMP and methanol.To this solution, introduced into a roll-mill, are added aluminum powder (400 mesh)... 

Much attention has been paid to the synthesis of fluorine-containing condensation polymers because of their unique properties (43) and different classes of polymers including polyethers, polyesters, polycarbonates, polyamides, polyurethanes, polyimides, polybenzimidazoles, and epoxy prepolymers containing pendent or backbone-incorporated bis-trifluoromethyl groups have been developed. These polymers exhibit promise as film formers, gas separation membranes, seals, soluble polymers, coatings, adhesives, and in other high temperature applications (103,104). Such polymers show increased solubility, glass-transition temperature, flame resistance, thermal stability, oxidation and environmental stability, decreased color, crystallinity, dielectric constant, and water absorption. 

The most important resins available for use as adhesives in high-temperature structural applications are polyimides (Pis) and polybenzimidazoles (PBIs), both of which are described later (see Sections 5.35 and 5.33). These resins are supplied as prepolymers containing open heterocyclic rings, which are soluble and fusible. At elevated temperatures, the prepolymers undergo condensation reactions leading to ring closure and the formation of insoluble and infusible cured resins. 

Potyimide adhesives S J SHAW Condensation and thermoplastic polyimides, imide prepolymers high-temperature stability... 

Addition resins are based on short, preimidized polymer chain segments similar to those comprising condensation polyimides. The prepolymer chains, which have unsaturated aliphatic end groups, are capped by termini which polymerize thermally without the loss of volatiles. 

The poly(amic acid) (V) prepared from pyromellitic dianhydride and 4,4 -diaminophenyl ether is a typical example of a high molecular weight prepolymer. The initial condensation product, poly(amic acid), is soluble in organic solvents and can be cast to films, which are subsequently cyclized to the insoluble polyimide (Vl).9... 

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