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Aromatic tetracarboxylic acids

Imides - Polyimides (PI) have been conventionally prepared by the chemical or thermal cyclodehydration of polyamic acids formed from the solution reaction of aromatic tetracarboxylic dianhydrides and aromatic diamines. The early PI were insoluble and relatively intractable. The polyamic acid was the processable intermediate. However, the polyamic acid precursor has two major shortcomings, hydrolytic instability and the evolution of volatiles during the thermal conversion to PI. In addition, residual solvent was left in adhesive tapes and prepregs to obtain tack, drape and flow. During the fabrication of components, the evolution of volatiles caused processing problems and led to porosity in the part. As work progressed on PI, other synthetic routes were investigated (e.g. reaction of esters of aromatic tetracarboxylic acids with diamines... [Pg.9]

This book reviews some of the results of investigations of chemical conversions of chloral and TNT to new aromatic di(poly)amines and aromatic tetracarboxylic acid dianhydrides useful for the preparation of new polyimides combining good thermal, mechanical and electrical properties with improved processability. [Pg.3]

Along with new aromatic diamines and tetramines based on chloral and its derivatives, new aromatic tetracarboxylic acid dianhydrides were developed. These products were prepared by the interaction of bis-phenols - chloral derivatives - with two-fold molar amounts of nitrophthalimides followed by transformation of bis-phthalimides, containing two ether bonds, into the corresponding aromatic tetracarboxylic acid dianhydrides [30] (Scheme 2.13). [Pg.8]

For thermal stability polypyromellitimides are somewhat inferior to polyimides based on the anhydrides of other aromatic tetracarboxylic acids. This is apparently due to the higher chlorine content per unit polymer weight in the former. [Pg.20]

Polyimides with better viscosity characteristics have been obtained from 3,3 -diamino-4,4 -bis(dimethylamino)-benzophenone and different aromatic tetracarboxylic acid dianhydrides [21] (Scheme 3.4). [Pg.21]

Reactions of 3,3 -diamino-4,4 -bis(dimethylamino)-benzophenone with the dianhydrides of aromatic tetracarboxylic acids (pyromellitic, benzophenone-3,3, 4,4 -tetracarboxylic and diphenyloxide-3,3, 4,4 -tetracarboxylic acids) were carried out using a two-stage process including room temperature reaction of starting monomers in NMP, formation of PCA and subsequent cyclodehydration of the... [Pg.21]

New representatives of such polyimides were prepared from TNT-based perfluoro-substituted m-phenylenediamines and different aromatic tetracarboxylic acid dianhydrides [9-12] in accordance with Scheme 5.2. Reactions were carried out in w-cresol using isoquinoline as catalyst. The reaction temperature was 160 °C and the reaction time 5 hours. [Pg.48]

Interaction of 2-niethyl-3,5-diaminodiphenylsulfide with aromatic tetracarboxylic acid dianhydrides was carried out in accordance with Scheme 5.6. Synthesis of the polyimides was carried out using two general procedures ... [Pg.57]

Diamino-6-(N-phthalimido)-toluene was reacted with aromatic tetracarboxylic acids, 3,3, 4,4 -tetracarboxydiphenyl ether, 3,3, 4,4 -tetracarboxybenzophenone and dianhydrides, dianhydride 6F and dianhydride A, using high-temperature polycondensation in w-cresol with quinoline as a catalyst (Scheme 5.8). [Pg.61]

Interestingly, aromatic tetracarboxylic acids themselves such as pyromellitic acid (PMA),3,3,4,4,-biphenyltetracarboxylic acid (BPA),4,4 -oxydiphthalic acid... [Pg.5]

JP 05311144 (Japanese) 1993 Heat-resistant adhesive compositions containing polyimide-siloxane block copolymers Ube Industries, Japan H Inoe, S Takabayashi, T Funakoshi, K Sonoyana Useful for Cu-clad laminates of printed circuit boards and tape-automated bonding with good flexibility and heat resistance Formulated compositions containing siloxane-imide block copolymers made from aromatic tetracarboxylic acids and aromatic diamines and aminosiloxanes... [Pg.91]

The softening point determined by thermomechanical methods may be as high as 500°C. A true ladder polymer can also be obtained by condensation of an aromatic tetracarboxylic acid or a dianhydride with an aromatic tetramine. An example is... [Pg.142]

A novel conjugated polymers, PI based on N, N , N , N substituted paraphenyl-enediamine and dianhydrides of aromatic tetracarboxylic acids, was successfully prepared via Suzuki coupling reaction. The polymer exhibits excellent solubility in common organic solvent, and has high thermal stability such as T j at 453°C in nitrogen atmosphere and T at about 140°C. [Pg.9]

In 1965, workers from DuPont first prepared a linear thermoplastic polyimide. When aromatic diamines are reacted with aromatic dianhydrides, aromatic tetracarboxylic acids, or dialkyl esters of aromatic tetracarboxylic acids, in a solvent such as DMF (Table 13.7), they were converted to a polyamic acid, which when heated, cured by cyclization (imide ring closure, or imidization). This ring closure is a condensation process, releasing either water, or an alkyl alcohol, or both [36]. [Pg.523]

Polycondensation is a typical method for polyimide syntheses, which need aromatic tetracarboxylic acids and aromatic diamines as monomers. Figure 10.1 shows that the polymerization process goes through two reactions The ring-opening polyaddition of aromatic diamines to aromatic tetracarboxylic dianhydrides in solution at room temperature gives soluble precursor polyamic acids, followed by solid-state thermal cyclodehydration to polyimides. [Pg.222]

Polyimides with aliphatic units in their main chain are generally obtained by thermal polycondensation by heating salts of aromatic tetracarboxylic acids and aliphatic diamines. Edwards and Robinson were the first to describe the preparation of an aliphatic polyimide by the fusion of a diamine with a diester of a tetracarboxylic acid. The reaction for the polyimide formation may be represented as follows [2] ... [Pg.317]

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]. [Pg.321]

By using monomers other than dianhydrides and diamines, a number of methods has been outlined to synthesize polyimides, for instance from tetracarboxylic acids and their half diesters. This method can be successfully applied to the preparation of aliphatic-aromatic polyimides by melt polycondensation of the salt from the diamine and an aromatic tetracarboxylic acid or half-diester (Scheme 8). The reaction achieved some importance when polyimides appeared in the 1950s as an alternative for uses such as... [Pg.559]

However, unlike the aromatic tetracarboxylic acid dianhydride that was dominant at the time, a compound having a five-numbered ring structure aliphatic was highly unusual. [Pg.77]


See other pages where Aromatic tetracarboxylic acids is mentioned: [Pg.145]    [Pg.61]    [Pg.64]    [Pg.67]    [Pg.993]    [Pg.396]    [Pg.16]    [Pg.20]    [Pg.993]    [Pg.60]    [Pg.313]    [Pg.111]   
See also in sourсe #XX -- [ Pg.8 ]




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Tetracarboxyl

Tetracarboxylic acids

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