Recent advances in thermosetting polyimides

Abstract

Addition type imide resins are finding increased use as matrix resins for advanced composites. Many different chemical approaches have been used to synthesize imide resins which are easy to process (similar to epoxies) but higher in temperature resistance. This paper outlines recent advances in thermosetting imide resin chemistry; however, only those concepts which have been accepted by the industry and the most promising research concepts are discussed, such as: endomethylenetetrahydrophthalimides acetylene terminated polyimides bismaleimides benzocyclobutenes.Of these, the bismaleimides are easiest to process. When used in combination with comonomers such a s bisallylphenyl compounds, bis-o-(propeny1phenoxy)benzophenones, benzocyclobutenes, etc., their toughness can be improved significantly to make them prime candidates as matrices for advanced composites and adhesives.

Methyl nadimide resins: Synthesis and characterization

“…An approximate 5-12% weight loss was observed in the temperature range of 220-400°C. The thermal transition of methyl nadimides can be summarized as ( 1 ) endo-exo isomerization; ( 2 ) a retro Diels-Alder reaction leading to formation of maleimide and methyl cyclopentadiene; ( 3 ) polymerization of methyl nadimides; and (4) polymerization of in-situ -generated maleimide and methyl cyc10pentadiene.l~ The transition in the temperature range of 220-400°C may be attributed to the curing of the methyl nadimides via a retro Diels-Alder reaction in which in situ formation of methyl cyclopentadiene and maleimide units takes place initially, followed by polymerization. Some of the methyl cyclopentadiene might have escaped as volatile, leading to weight loss during the exothermic transitions.…”

“…Thermoset addition polyimides, [1][2][3] such as maleimide and nadimide end-capped resins, have been commercially exploited in the past as high-temperature-resistant matrices for advanced composites. PMR-15, which is an alcoholic solution of the monomethyl ester of 5-norbornene-2,3-dicarboxylic acid, the dimethyl ester of benzophenone tetracarboxylic acid, and 4,4'-diaminodiphenyl methane has been extensively investigated in the past.…”

Modification of two-component bismaleimide resin by blending (meth)allyl compounds as third components

“…1 During curing, DBA copolymerizes with BDM via an enetype linear chain-extension reaction followed by the Diels±Alder reaction. The brittleness of the cured resin is improved, compared with the conventional bismaleimide resins.…”

Investigation of readily processable thermoplastic-toughened thermosets. I. BMIs toughened via a reactive solvent approach

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17] Various approaches to toughening have been investigated, 15 -19 and many High-performance thermosets are of interest as studies on the mechanisms of toughening have matrix resins for composites for structural applibeen undertaken and have been thoroughly recations. However, the inherent brittleness of therviewed (for example, Huang et al 20 ).…”