Nadic anhydride

A number of special purpose resins are available which employ somewhat unusual acids and diluents. A resin of improved heat resistance is obtained by using Nadic anhydride, the Diels-Alder reaction product of cyclopentadiene and maleic anhydride Figure 25.5). 

The methylated maleic acid adduct of phthalic anhydride, known as methyl nadic anhydride VI, is somewhat more useful. Heat distortion temperatures as high as 202°C have been quoted whilst cured systems, with bis-phenol epoxides, have very good heat stability as measured by weight loss over a period of time at elevated temperatures. The other advantage of this hardener is that it is a liquid easily incorporated into the resin. About 80 phr are used but curing cycles are rather long. A typical schedule is 16 hours at 120°C and 1 hour at 180°C. 

When cured with room temperature curing system these resins have similar thermal stability to ordinary bis-phenol A type epoxides. However, when they are cured with high-temperature hardeners such as methyl nadic anhydride both thermal degradation stability and heat deflection temperatures are considerably improved. Chemical resistance is also markedly improved. Perhaps the most serious limitation of these materials is their high viscosity. 

To improve the processability of PI and to alleviate or eliminate volatiles, work began in the late 1960 s under NASA Lewis sponsorship (23), to end-cap oligomers with reactive groups. The first report involved the use of 3,6-endomethylene-l,2,3,6-tetrahy-drophthalic anhydride (5-norbornene-2,3-dicarbo ylic anhydride, nadic anhydride) and alkyl derivatives thereof (e.g. citraconic anhydride) and 1,2,3,4-tetrahydrophthalic anhydride (4-cyclohexene-1, 2-dicarboxylic anhydride) as the reactive end group on imide oligomers (23-25). This initial effort led to the development of P13N [with T for polyimide, 13 for Mn of 1300g/mole and N for nadic end cap] whose structure is shown below. 

Nadic anhydride was also used to terminate an amic acid oligomer prepared from the reaction of 3,3 , 4,4 -benzophenonetetra-carboxylic dianhydride and 3,3 -methylenedianiline where the... 

Materials Description. Three CIBA-GEIGY epoxy/hardener systems were studied Araldite 6010/906, Araldite 6010/HY 917 and Araldite 6010/972 with stoichiometries 100/80, 100/80 and 100/27, respectively. Araldite 6010 was a DGEBA epoxy resin. The hardeners 906, HY 917 and 972 were, respectively, methyl nadic anhydride (MNA), methyltetrahydro phthalic anhydride (MTPHA) and methylene dianiline (MDA). These systems were investigated previously for the matrix controlled fracture in composites (6-8). The curing cycles used can be found in (6). The ideal chemical structures of the systems are shown in Table I. Neat resins were thoroughly degassed and cast into 1.27 cm thick plates for preparation of test specimens. 

Norbomene end-capped polyimide oligomers (trade name LARC) are obtained by including 5-norbomene-2,3-dicarboxylic anhydride (nadic anhydride) (XLVII) in the polymerization reaction between a dianhydride and diamine [de Abajo, 1988 Hergenrother, 1987]. Heating the oligomer at 270-320°C results in a thermoset product. The main reaction... 

Nadic anhydride introduces polar groups into the polymer. These polar groups promote adhesion. However, it has a greatly different polymerizability from that of a norbornene monomer having no polar group. Therefore, the copolymerization reaction does not sufficiently occur. Better results are obtained with tetracyclododecene instead of norbornene (3). 

JP 04220431 (Japanese) 1992 Tough polyimides and prepregs and fiber reinforced plastics Toray Industries, Japan M Eno, K Tobukuro Toughened fiber reinforced prepregs Polyimide-siloxanes prepared from BTDA and aminosiloxanes with nadic anhydride termination... 

The first nadimide end-capped oligomers were prepared using the unbalanced classical reaction of a dianhydride (BTDA) with an excess of diamine (MDA) and a quantity of nadic anhydride (NA) corresponding to the diamine excess (Fig. 4). The reaction was performed in NMP with a molecular ratio calculated in order to get a Mn of 1300 g mol-1 [12]. However the amic acid intermediate is not stable enough to allow a long term storage of the NMP solution... 

These drawbacks explain the development of a new concept introduced by a NASA team. According to this concept polymerization of monomeric reactants (PMR), a bisortho ester acid replaces the dianhydride and the monomethyl ester of the nadic acid is used instead of the nadic anhydride as shown in Fig. 5. These esters and the diamine are dissolved in methanol (or in a metha-nol/isopropanol mixture) in a molar ratio calculated to get the desired theoretical molecular weight [14]. These mixtures of reactants are currently used for the preparation of composites and adhesives [15a,b]. 

Moad also notes that the most common grafting modifications made to polyolefins are via maleic anhydride, maleate esters, styrene, maleimides, acrylates and their esters, and vinyl silanes. Other polymer systems (Fink, 2005) that undergo grafting are polystyrene/maleic anhydride (useful for PA6/PS blends), PVC/butylmethacrylate (for improved processi-bility), PET/nadic anhydride, starch/vinyl acetate and starch/methyl acrylate (for improved water resistance). 

Maleic anhydride [2] is discussed in 8.1 and nadic anhydride in [27]. Potassium hydrogeiunaleate forms a cyclic structure containing a strongly hydrogen bonded hydrogen atom midway between the two oxygen atoms. The assignment of the vibrational spectra has proven controversial [57] ( 9.3.1.5). 

S.F. Parker, K.P.J. Williams, D. Steele H. Herman (2003). Phys. Chem. Chem. Phys., 5, 1508-1514. The vibrational spectra of norbomene and nadic anhydride. 

Fig. 10.23 The chemistry of PMR-15. The first stage is imidisation of the reactants, nadic anhydride monomethyl ester (NE), methylene dianiline (MDA) and 3,3 ,4,4 -benzophenonetetracarboxylic acid dimethyl ester (BTDE). The second stage is cross-linking of the norbomene end-caps.

The structures and corresponding calculated MI values are given in Table 7 (nos. 1-5). Mesophases were observed for scores of MI=12 and 13 but not for the odd structures (MI range 9.5-11). In addition, a series of imide-amide oligomers were synthesised with molecular weights above 1000, in which the terminal groups were nadic anhydride. Mis ranged from 8.3 to 10.7 but no positive identification of mesophases were made in any of these (Table 7, nos. 6-9)... 

NA=nadic anhydride BAPS=bisaminophenoxy phenylsulphone BDTE=benzene tetradicarboxylic diester TPA=terephthalic acid IPA=isophthalic acid BAPP=bisaminophenoxy phenyl 2-2 propane a An LC phase... 

Beilstein Handbook Reference) 5-Norbornene-2,3-dicarboxylic anhydride, methyl- BRN 0162395 EINECS 246-644-8 Epicure NMA Hardener HY906 HSDB 6093 Kayahard MOO MEA 610 4,7-Methanoisobenzofuran-1,3-dione, 3a,4,7,7a-tetrahydro-methyl-, Methendic anhydride Methyl-5-norbornene-2,3-dicarboxylic anhydride Methyl nadic anhydride Methylbicyclo(2.2.1)heptene-2,3-dicarboxylic anhydride isomers Methylendic anhydride Methylnorbornene-2,3-dicarboxylic anhydride Nadic methyl anhydride NMA TK10 524 XMNA. 

Dimethylamino)benzoic acid 3- 246-644-8 Methyl nadic anhydride 2489... 

A 4 methyl yclohexene-l,2-dicarboxylic acid anhydride B methyl endomethylene-tetrahydrophthahc anhydride (Methyl Nadic Anhydride)... 

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