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.
SynopsisBismaleimides polymerize a t elevated temperatures, forming highly crosslinked, high temperature-resistant polymers. From the decrease of the v(H-C=) band at 3100 cm-1, rate constants and activation energies of the polymerization of four homologous aliphatic bismaleimides were determined. Up to a 20-30% conversion, the polymerization is pseudofirst order. An almost linear correlation between the activation energy and the number of methylene groups in the sequence between the maleimide residues was found.
ZusammenfassungBismaleinimide polymerisieren spontan bei hoheren Temperaturen unter Bildung vernetzter, hochtemperaturbestandiger Polymerer. Aus der Abnahme der Extinktion der v(H--C=>Bande bei 3100 em-' wiihrend der Polymerisation wurden Geschwindigkeitskonstante und Aktivierungsenergie der Polymerisation von vier homologen aliphatischen Bismaleinimiden bestimmt. Bis zu einem Umsatz von 20-30% ist die Polymerisation pseudo-erster Ordnung. Zwischen der Aktivierungsenergie und der Zahl der Methylengruppen in der Brucke zwischen den Maleinimideinheiten wurde in dem untersuchten Bereich eine nahezu lineare Abhangigkeit gefunden.
RbUIllCLes bis-imides mal6iques polym6risent spontanement h hautes temperatures avec la formation de pclymbres entrelac6s, qui sont resistants A des temp6ratures Blevees. A l'aide la diminuation de l'extinction de la bande de valence H-C-A 3100 cm-l, la constante de vitesse ainsi que 1'6nergie d'activation de quatre homologues aliphatiques bisimides mal6iques ont BtB d6terminCes pendant la polymerisation. La reaction, pendant laquelle 20 L 30 pour cent des bis-imides maleiques se sont polymeris6s, est "pseudo premier ordre." Une relation L peu prbs lin6aire a ete trouvee-dans le domaine ou les mesures ont 6tk effectu6es-entre l'energie d'activation et le nombre de groupes methylbne dans le pont entre les unites des imides malkiques.
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