Nadic methyl anhydride epoxy

Figure 2. Solid-state spectra of four different epoxies (hosed on the resin diglycidyl ether of bisphenol-A) are compared with the liquid-state spectra of their respective unreacted components, The chemical compositions are in Table I. Here the epoxies are identified by their main curing agent (a) PIP—piperidine (b) MPDA—metaphenylene diamine (c) HHPA—hexahydro-phthalic anhydride (d) NMA—nadic methyl anhydride.

Garroway, Ritchie, and Moniz 70 continued the characterization of epoxy polymers with respect to molecular motion using variable temperature, solid state C-13 NMR. DGEBA was the epoxy of interest. The DGEBA was cured with piperidine, m-phenylene diamine, hexahydrophthalic anhydride and nadic methyl anhydride. The piperidine cured DGEBA had the best resolved polymer spectra. This system... 

TABLE 4.3 Thermal Weight Loss, Weight Percent, of Nadic Methyl Anhydride Cured Epoxy Novolac Resin (Cured 2 h at 90°C, 4 h at 165°C, and 16 h at 200°C)4... 

After the primary amines, acid anhydrides are the next most important class of epoxy curing agents, although these are not used as often in adhesive systems as they are in casting compounds, encapsulants, molding compounds, etc. The most common types of anhydrides are hexahydrophthalic anhydride (HHPA), phthalic anhydride (PA), nadic methyl anhydride (NMA), and pyromellitic dianhydride (PMDA), although there are several others. Chemical structures of several anhydrides are illustrated in Fig. 5.6. 

Nadic methyl anhydride (NMA) is the most versatile of all the anhydrides. NMA is a liquid of viscosity about 200 cP at room temperature, and it is readily soluble in epoxy resins. The mix ratio is 60 to 90 pph when used with a liquid DGEBA epoxy resin. At 60 pph and with no catalyst, the working life is about 2 months and with the incorporation of 0.5 pph DMP-30 as an accelerator, the working life reduces to 4 to 5 days. 

It has also been shown in several studies that the combination of stress, temperature, and moisture can accelerate the hydrolytic instability of certain epoxy adhesives. In an FTIR study of the effect of moisture on DGEBA epoxy cured with nadic methyl anhydride, spectra changes were observed in stressed specimens aged for 155 days at 80°C and 100 percent RH.47 This was attributed to the slow, stress-induced hydrolysis of ester groups. In another study,... 

Later, McPherson (39) demonstrated that the Inclusion of a CTBN/liquid epoxy adduct enhanced both the flexibility and adhesion of a dimer acid flexibllized epoxy/brominated epoxy mixture when cured with a combination of chlorendic and nadic-methyl anhydrides. With an epoxy-glass laminate as substrate, such mixtures were coated at 0.5-2.0 mils thickness, cured, sensitized and copper plated (1.5 mils) by an electroless process. 90 peel testing (2 inches/mln. rate, 25 C) gave 14.0 pli peel force where 5.0 pli is considered normal. 

A linear-chained epoxy resin was formulated from phenyl glycidyl ether and nadic methyl anhydride, catalysed by benzyldimethylamine (248). An IR fibre-optic probe was used to follow the conversion of a thermosetting tetrafunctional epoxy resin in which the hardener was an aromatic diamine and a carboxylic dianhydride. A polymerisation system consisting of a cycloaliphatic diepoxide, epoxidised natural rubber (ENR), glycidyl methacrylate (GMA) and a cationic photoinitiator, triphenylsulfonium hexafluoro-antimonate, was studied (75). Multifunctional epoxy/ amine formulations (Epon 825 plus 4,4 -methylene-... 

Alinear-chained epoxy resin was formulated from phenyl glycidyl ether and nadic methyl anhydride catalysed by benzyldimethylamine. Intermolecular polymerisations were modelled as a parallel set of propagation reactions. FTIR spectroscopy was used to determine the concentrations of the oxirane, anhydride and ester moieties within the resin as a function of time for two isothermal cures. Data analyses yielded the propagation rate constant as a function of temp, and the concentration of initiator, including contributions fl om impurities within the resin. Results obtained compared favourably with measurements on fractionated resins, using GPC. Population density distributions are described by Poisson molar distributions for this resin. 25 refs. 

Acid anhydride curing agents, especially the liquid anhydrides, are particularly important for epoxy resins. They cure at elevated temperatures but offer long pot life, good electrical properties, and heat resistance. Typical of these agents are phthalic anhydride and nadic methyl anhydride. The high-temperature properties of resin systans cured with these materials are better than those of resin systems cured with... 

Fig. 8. Effects of accelerator on epoxy/nadic methyl anhydride cure.

Recently, exfoliated layered silicate-epoxy nanocomposites have been prepared from the diglycidyl ether of bisphenol-A and nadic methyl anhydride (12). The dynamic storage modulus of the nanocomposite containing 4 vol %... 

Cyclic acid anhydrides are widely employed as curing agents for epoxy resins. Both mono- and dianhydrides are used. Examples of anhydrides which find application are maleic anhydride (MA) (XIX), dodecenylsuccinic anhydride (DDSA) (XX), hexahydrophthalic anhydride (HPA) (XXI), phthalic anhydride (PA) (30(11), pyromellitic dianhydride MDA) (XXIII), nadic methyl anhydride (NMA) (a mixture of maleic anhydride adducts of methylcyclopentadienes cf.. Section 10.2.2.3) (XXIV) and chlorendic (HET) anhydride (XXV see also Section 102.2.3). 

The cure of epoxidized novolaks, prepared via the reaction of Ph0H/CH2=0 copolymer with epichlorohydrin, in the presence of Nadic methyl anhydride, was studied by differential scanning colorimetry (DSC) [121]. The use of DSC to study other epoxy resin curing systems has been reported in the literature. 

For example, the strain-to-failure of the network formed by curing DGEBA with nadic methyl anhydride (NMA) and the catalyst benzyldimethylamine (BDMA) decreases from 12 % to 6 % after 56 days at 23 °C [5]. Physical aging has also been observed in amine cured epoxy resin systems and in an uncross-linked 28,000 g/mol linear epoxy resin tested under wet conditions [6]. In contrast, DGEBA homo-polymerized with piperidine (subsequently... 

Crosslinking of epoxy plastics through the hydroxyl groups of the repeat unit is used for prepolymers with low epoxide group contents. The most common curing agent is phthalic anhydride although other acid anhydrides such as tetrahydrophthalic, nadic methyl, and chloroendic anhydrides are used in specialty applications ... 

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. 

Anhydrides are also high temperature curing agents. The reaction with epoxy resins is slow in the absence of an accelerator, and requires quite large quantities. Typical substances used include methyl nadic anhydride and hexahydrophthalic anhydride. (Methyl nadic anhydride is a convenient liquid at room temperature, whereas nadic anhydride is a solid.)... 

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