Thermoset polyimide

Diesters of Tetracarboxylic Acids with Diamines. Dianhydrides react with alcohols at a moderate temperature, producing the tetracarboxyhc acid diesters. Ben2ophenonetetracarboxyhc acid diester (BTTA diester) is obtained from B I DA as a mixture of three positional isomers. Partiy because it is an isomeric mixture, the diester of BTTA is soluble in methanol at high concentrations. A state-of-the-art thermoset polyimide,... 

Diels-AIder Copolymers. The Diels-Alder reaction can also be employed to obtain thermosetting polyimides. If bismaleimide (the bisdienophile) and the bisdiene react nonstoichiometricaHy, with bismaleimide in excess, a prepolymer carrying maleimide terminations is formed as an intermediate, which can then be cross-linked to yield a temperature-resistant network. 

The thermoset polyimides are a family of heat-resistant polymers with acceptable properties up to 260°C (500°F). They are unaffected by dilute acids, aromatic and ahphatic hydrocarbons, esters, ethers, and alcohols but are attacked by dilute alkahes and concentrated inorganic acids. 

Bis-maleimide resins composed of BMI and diamines have been reported in the early 1960s in the patent literature. Since that time, a number of patents have appeared describing improvements in their properties and uses [3]. Although many bis-maleimide resins are commercially developed, relatively few reports of their use as adhesives are to be found in scientific journals [4-10]. Improvements of maleimide resins are mirrored in the improvements of thermosetting polyimides. For example, the method of in situ polymerization of monomer reactants (PMR method) was developed [6]. 

Stenzenberger H. D. Thermosetting Polyimides from Bismaleimides via Diels-Alder Reaction in Polyimides Other High-Temp. Polym., Proc. Eur. Tech. Symp., 2nd" 1991 215, Eds. Abadie M. J. M. and Sillion B., Pb. Elsevier Amsterdam... 

One resin based on the BTDA/ODA backbone and 2-aminobiphenylene as an endcapper was thought to be such a resin (126). High quality laminates could be fabricated, but the Tg of the crosslinked polymer was lower than expected and therefore thermal oxidative stability was poor. The chemical structure of this thermosetting polyimide is given in Fig. 42. 

As in all thermosetting polyimides, the diamine and the tetracarboxylic dianhydride employed to build the backbone can be varied. Alteration of the diamine, tetraacid or both, allow the modification of the polyimide s melting point and solubility. Of interest to the end user is the influence of chemical structure on the melting transition of the prepolymer and the Tg of the fully cured product. Lowering the uncured Tg means increasing flow and, in most... 

In Table 1, the moisture uptake of cured and uncured Navy P3-2300-PE resin after 24 hours of immersion is compared to a number of other high-temperature polymer resins. The moisture uptake of the Navy P3 oligomer is nearly identical to that of the commercial P3 thermoplastic. Other commercial thermoplastics, such as poly(ether ether ketone), with very similar chemical compositions, exhibit similarly low levels of moisture uptake. On the other hand, the Navy P3 resins absorbs about 85% less water than the commercial polyimide Kapton HN. Since thermosetting phenyl ethynyl end-capped polyimides have moisture uptake characteristics that are similar to Kapton HN, with around 3% weight gain on exposure to 95% relative humidity (77), void-free composites based on Navy P3 resins should exhibit greatly reduced moisture uptake compared to those based on thermosetting polyimides. 

A new thermoset polyimide introduced by Ciba-Geigy is related to PMR-15. The oligomer is end capped with allylnorbomenedicarboxyl anhydride. 

Polyimide, the thermal conductivity of which is low, is used for circuit boards. However, circuit boards require high thermal conductivity, recently. The combination of polyimide and Cu must improve thermal conductivity. The polyimide of the polyimide/AI PGM is thermoplastic. The sintering temperature of Cu is higher than that of Al. A thermoplastic cannot be used for the formation of a polyimide/Cu PGM, as a Cu layer could not be sintered densely. A thermosetting polyimide was selected for that PGM. 

A polyimide/Cu FGM was prepared by stacking different compositions of Cu and thermosetting polyimide powders using a spark plasma system. The consolidation temperature was about 520 C for the Cu layer and 390°C for the polyimide layer. One graded layer or two graded layers resulted in cracks. There were no cracks in the FGM prepared by stacking three graded layers. The thermal conductivity of thin... 

When an automotive chemist chooses a polymer for dynamic sealing, he or she will have to consider the conditions present in Table 6.1. The two main polymers utilized today for these applications are the thermoset polyimides and polyetheretherketones. Polytetrafluoroethylene is also used for less severe applications. Wear test data are collected on an apparatus in which three circular pins of the polymer being examined... 

C.-H. Chuang. Solvent free low-melt viscosity imide ohgonaers and thermosetting polyimide composites. US Patent 7015304, assigned to The United States of America as represented by the Administrator of the National Aeronautics and Space Administration (Washington, DC) N/A (, March 21, 2006. 

Two types of thermoset polyimides are currently prepared commercially. They are based on low molecular weight bisimides such as bismaleimides or bis-5-norbomene-2,3-dicarboximides. Due to unsaturations, the materials crosslink by a free-radical mechanism into tight networks. Michael-type additions of primary and secondary amines to the bismaleimides are often used to... 

KINEL molding powders and KERIMID 601 leuninating resins dre based on a thermosetting polyimide, which cures without evolution of volatiles. KINEL compounds are transformed by compression, transfer, or extrusion molding into void-free parts, whose thermomechanical properties exceed those attainable from conventional thermoplastics or thermosets. 

Thermosetting polyimides are one of the highest performing engineering plastics, exhibiting superior performance in applications requiring low wear and long life in severe environments. Polyimide materials feature ... 

H. Liu, Y. Li, T. Wang, and Q. Wang, In situ synthesis and thermal, tribological properties of thermosetting polyimide/graphene oxide nanocomposites. Journal of Materials Science, 47 (4), 1867-1874,2012. 

---