Polyimides addition

PETI-5 3,4 -Oxydianiline, 1,3-bis (3-amino phenoxy benzene) and 3,3, 4,4 -biphenyl tetracarboxylic dianhydride encapped with 4-phenylethynyl pthalic anhydride Phenyl ethynyl 270/250 [141-143] 

PMR-I (PMR 15, PMR30, PMR 50) Monomethyl ester of 5-norbornene-2,3 dicarboxylic acid (Nadic ester), dimethyl ester of 3,3, 4,4 -benzophenone tetracarbo xylic acid dianhydride (BTDA) and 4,4 -methylene dianiline Mole ratio 2 2.087 3.087 Nadic 340(395)1316 [144-146] 

LARC- RP46 Modified PMR-I formulation replacement of MDA by 3,4 -oxy dianiline Nadic 280(395)7300 [147,148] 

PMR-II 6F PMR BTDA of PMR (I) is replaced by half ester of 4,4 -(hexafluoroisopropylidene)-dipthalic acid (HFDF) Nadic 350(390)7316 [149,150] 

---

Additive Polyimides. Rhc ne-Poulenc s Kin el molding compound and Kerimid impregnating resin (115), Mitsubishi s BT Resins (116), and Toshiba s Imidaloy Resin (117) are based on bismaleimide (4) technology. Maleic anhydride reacts with a diamine to produce a diimide oligomer (7). Eurther reaction with additional diamine (Michael addition) yields polyaminohismaleimide prepolymer with terminal maleic anhydride double bonds. Cure is achieved by free-radical polymerization through the terminal double bonds. 

BMI or aminobismaleimides or addition polyimides from the reaction of a diamine and a bismaleimide to make a prepolymer that is then cured by an excess of diamine. This type is particularly convenient for the manufacture of thick parts. 

The main processing methods for addition polyimides are machining compression, transfer and injection moulding encapsulation, impregnation, stratification, filament winding, varnishing, sintering. 

Additional polyimide derivatives effective as adhesives are described by the authors (1) in earlier investigations. 

Addition poly(imide) oligomers are used as matrix resins for high performance composites based on glass-, carbon- and aramide fibers. The world wide market for advanced composites and adhesives was about 70 million in 1990. This amounted to approximately 30-40 million in resin sales. Currently, epoxy resins constitute over 90% of the matrix resin materials in advanced composites. The remaining 10% are unsaturated polyester and vinylester for the low temperature applications and cyanate esters and addition poly(imides) for high temperatures. More recently thermoplastics have become important and materials such as polyimides and poly(arylene ether) are becoming more competitive with addition polyimides. 

The applications for addition polyimides are for electronic/electrical materials such as printed circuit boards and insulators, as matrix resins for structural composites in aircraft and as thermal insulation materials. Recently the market for polyimide based structural composites has suffered from the termination and reduction of military aircraft programs. However, the possible emergence of the High Speed Civil Transport program (HSCT) may offer an opportunity for addition polyimides (2). 

More recently PMR resin modifications were developed because MDA used in PMR-15 is potentially hazardous. PMR-15 which is the most widely used addition polyimide in composites, is under pressure because of the new OSHA regulations. The target is to employ diamines which are not toxic or to prereact the diamines to avoid the presence of free diamines. 

Bismaleimides are an important class of addition polyimides. They are known for their excellent processability and balance of thermal, electrical and mechan-... 

---