Addition type polyimides

Adhesive Film, Hot Melt, Addition Type Polyimide, for Foam Sandwich Structure, -67 to 450°F... 

The historically-firet condensation polyimides have recently been complanented by a second class of resins - addition-type polyimides. KINEL conqpounds and KERIMID 601 laminating resin are menbers of this new family of polyimides. Ch ically they eure designated polyaminobismaleimides (PABMs) ... 

Delvigs, P. Serafini, T. T. and Li tsey, G. R., "Addition-Type Polyimides from Solutions of Monomeric Reactants", NASA TN D-6877 (1972) Materials Review for 72 Proceedings of the National Symposium emd Exhibition, Science of Advanced Materials and Process Engineering Series, (17) p, III-B-7-1. 

For durable bonds, adhesives should be tough. However, many high temperature adhesives (addition-type polyimides, bismaleimides (BMI), and acetylene-terminated resins) are brittle and need to be toughened by elastomers. 

FM-35 American Cyanamid Addition-type polyimide film on glass cloth with metal fillers. 

Addition-type polyimides, which are thermosetting resins, were developed to improve the processability of polyimides, but their thermal stability is severely degraded by the presence of aliphatic bonds in place of the aromatic nuclei. However, the adhesive strength has been evaluated for the bismaleimide- (Section 4.3.4.1), bisnadimide- (Section 4.3.4.2) and acetylene-terminated (Section 4.3.4.3) imide oligomers. 

The norbornene concept was further developed by NASA Lewis Research Center and culminated in the so-called PMR-concept, a novel class Of addition-type polyimides formed by in situ polymerization of monomeric reactants. 5 jhe reaction sequence36-37 involves aromatic diamine, S-norbornene-2,3-dicarboxy1ic acid monoalkyl ester and dialkyl ester of an aromatic tetracarboxylic acid which produces methanol, water, and the following intermediates [6]. 

C. Addition-Type Polyimides (Maleimide-based Polyimides)... 

Polyimides are the highest-temperature polymer in general advanced composite use, with a long-term upper temperature limit of 232°C (450°F) or 316°C (600°F). Two general types are condensation polyimides, which release water during the curing reaction, and addition type polyimides, with somewhat easier process requirements. 

In addition to Nafion-based catalyst layers, additional types have been developed, including CLs with different ion exchange capacities (lECs) [57,58] or with other hydrocarbon-type ionomers such as sulfonated poly(ether ether ketone) [58-60], sulfonated polysulfone [61,62], sulfonated polyether ionomers [63], and borosiloxane electrolytes [64], as well as sulfonated polyimide [65]. These nonfluorinated polymer materials have been targeted to reduce cost and/or increase operating temperature. Unfortunately, such CLs still encounter problems with low Pt utilization, flooding, and inferior performance compared wifh convenfional Nafion-based CLs. 

Nevertheless, further detailed information was unavailable on the polyimide synthesis from nylon-salt-type monomers that is referred to as salt monomer method , and this method was not really recognized as a simple synthetic method of both aromatic and aliphatic polyimides. In addition, many polyimide investigations have mainly been concentrated on aromatic polyimides, and little information is available about aliphatic polyimides [13-18] that are also potential candidates for engineering plastics. 

One drawback with addition-type polymers is that the cured adhesive tends to be brittle. Attempts to toughen addition polyimides have met with some success, though improvements in this area are needed. The development of systems exhibiting the same level of toughness as today s state-of-the-art epoxy adhesives is a goal for the future. 

Compression molding involves placing a material, usually in powder form, into the cavity of a heated mold (250OC) and applying heat (up to 350 C) and pressure (3000-5000 psi).56 This processing method can be used for the addition-type and thermoplastic polyimides. 

In addition to carbon and glass fibers ia composites, aramid and polyimide fibers are also used ia conjunction with epoxy resias. Safety requirements by the U.S. Federal Aeronautics Administration (FAA) have led to the development of flame- and heat-resistant seals and stmctural components ia civiUan aircraft cabias. Wool blend fabrics containing aramids, poly(phenylene sulfide), EDF, and other inherently flame-resistant fibers and fabrics containing only these highly heat- and flame-resistant fibers are the types most frequently used ia these appHcations. 

Angeltr—>has briefly reported in a patent the addition of metal ions to several types of polyimides. The object of the invention was a process for forming particle-containing (transparent polyimide shaped structures. Unlike the work discussed previously, all of the metals were added in the form of coordination complexes rather than as simple anhydrous or hydrated salts. The properties of only one film (e.g. cast from a N,N-dimethylformamide(DMF) solution of 4,4 -diaminodiphenyl methane, pyromellitic dianhydride and bis(acetylacetonato)-... 

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 addition to alkenes normally leads to unstable adducts that lose carbon dioxide under the reaction conditions. The intramolecular cycloaddition of the sydnone (30) takes place at room temperature, however (Equation (5)) and the cycloadduct (31) has been characterized <86HCA927>. The unstable species formed by the loss of carbon dioxide are also azomethine ylides. It is therefore possible for a second 1,3-dipolar addition to take place, as illustrated in Scheme 6 for the reaction of 3-phenylsydnone with Al-phenylmaleimide <86TL317,92JA8414>. This 2 1 addition has been used as the basis of a synthesis of polyimides. Imides of the type (32) were used as the dipolarophiles and their reaction with 3-phenylsydnone gave linear polymers <87MM726>. 

Walch et al. 13>80> determined the hyperfiltration properties of polyimide membranes 29. The polyamic acid-type prepolymer 30 were prepared by the addition... 

---