Epoxy resins acid anhydrides

Glycidyl ether epoxy resin Acid anhydride + (race of organic phosphonium salt — ... 

Thermoset plastics have also been pyrolysed with a view to obtain chemicals for recycling into the petrochemical industry. Pyrolysis of a polyester/styrene copolymer resin composite produced a wax which consisted of 96 wt% of phthalic anhydride and an oil composed of 26 wt% styrene. The phthalic anhydride is used as a modifying agent in polyester resin manufacture and can also be used as a cross-linking agent for epoxy resins. Phthalic anhydride is a characteristic early degradation product of unsaturated thermoset polyesters derived from orf/io-phthalic acid [56, 57]. Kaminsky et al. [9] investigated the pyrolysis of polyester at 768°C in a fiuidized-bed reactor and reported 18.1 wt% conversion to benzene. 

Figure 3.4 Anhydride-curing mechanism for epoxies (a) reaction of hydroxyl group (from epoxy resin) with anhydride (b) reaction of carboxylic acid group with epoxy (c) reaction of...

Resin, (Epoxy - Maleic Acid Anhydride - Methacrylic Rigidex 50 ... 

Epoxy Resins. Epoxy resins (qv) are used to cross-link other resins with amine, hydroxyl, and carboxyHc acid (or anhydride) groups. The epoxy group, properly called an oxkane, is a cycHc three-membered ether group. By far the most widely used epoxy resins in coatings are bisphenol A (BPA) (4,4 -(l-methylethyHdene)bisphenol) [80-05-7] epoxy resins. 

Table 2. Structure and Properties of Aromatic Diamines and Acid Anhydrides Used in Epoxy-Matrix Resins...

The reactions of carboxyUc acids and anhydrides with epoxy resins have been extensively studied in a variety of investigations, particularly References 27—31. The general reaction of epoxide resins and anhydrides is... 

The linear polymer formed is cured hy cross-linking either with an acid anhydride, which reacts with the -OH groups, or hy an amine, which opens the terminal epoxide rings. Cresols and other hisphenols are also used for producing epoxy resins. 

For this use, the preferred powders are based on acrylic, epoxy or polyester and epoxy resins. For best colour, epoxy resins are crosslinked with anhydrides of dicarboxylic acids in the straight epoxy coatings, or with saturated polyesters of high acid content in the epoxy-polyester type. Acrylics contain epoxide rings via, for example, glycidyl methacrylate (CH2=C(CH3) —CO—O—CHj—CH —CH2), and these groups crosslink... 

By contrast with tertiary amines used in catalytic quantities, primary and secondary amines or acid anhydrides may be used to bring about the cure of epoxy resins by reaction in stoichiometric proportions. A typical amine curing agent used at this level is diaminodiphenylmethane (DDM), which reacts with an individual epoxy-group in the way shown in Reaction 4.17. 

Epoxy (Anhydride-Cured) Epoxy resins may be crosslinked with various anhydrides by using a tertiary amine accelerator and heat. These cured polymers generally have good chemical resistance especially to acids. 

Cyclic acid anhydrides such as maleic, dodecylsuccinic, hexahydrophthalic, phthalic, phyromellitic, etc. are widely employed as curing agents for epoxy resins. They form esters with epoxy resins. These resins have better thermal stability and good electrical insulation and chemical resistance expect to alkalis. 

Curing agents account for much of the potential hazard associated with use of epoxy resins. There are several major types of curing agents aliphatic amines, aromatic amines, cycloaliphatic amines, acid anhydrides, polyamides, and catalytic curing agents. The latter two types are true catalysts, in that they do not participate in the curing process. 

Fawcett IW, Taylor AJN, Pepys J Asthma due to inhaled chemical agents—Epoxy resin systems containing phthalic acid anhydride, trimellitic acid anhydride and triethylene tetramine. Clin Allergy 7 1-14, 1977... 

With a carboxylic add anhydride S g of the resin prepared according to a) are melted in a beaker at 120 °C and 1.5 g of phthalic acid anhydride (0.6-0.8 equivalents per equivalent of epoxy groups) are stirred into the melt.The mixture is held at 120 °C for 1 h (after this time the resin is still soluble in acetone or chloroform) and then cured at 170-180 Cfor1-2h. 

Crosslinking of epoxy resins with carboxylic acid anhydrides is catalyzed by tertiary amines thus,if 50 mg /V,/V-dimethyl aniline are added to the initial mixture in the above example, the curing process is already complete after 1 h at 120 °C. 

On the other hand, epoxies cured with acid anhydrides and phenolic resins exhibit little or no reactivity when stored in direct contact with explosives and propellants. 

An interesting approach to maleimide-terminated phenoxy resin has recently has described (42). para-Maleimidobenzoic acid was reacted with diglyci-dylbisphenol-A epoxy resin in the presence of catalyst to provide the bismale-imide of Fig. 13. Instead of diglycidyl bisphenol-A, linear epoxy resin pre-polymers can be used in this reaction to form a maleimide terminated phenoxy resin. Another suitable functionalized monomaleimide is m- or p- N-(hydroxyphenyl) maleimide which is synthesized from maleic anhydride and m-aminophenol in DMF as a solvent at 70 °C. The purified hydroxyphenyl maleimide was reacted with epoxy resin to form novel BMIs as outlined in Fig. 14. The new BMI and phenoxy oligomers polymerize at temperatures of 200-220 °C, but the cure temperatures can be significantly lowered when catalysts such as imidazoles or triphenylphosphine are added. The cured homopolymers show Tg of 140 and 230 °C for the n = 2 and the n = 1 polymer, respectively(43). 

In Chapter 2 the DSC technique is discussed in terms of instruments, experimental methods, and ways of analysing the kinetic data. Chapter 3 provides a brief summary of epoxy resin curing reactions. Results of studies on the application of DSC to the cure of epoxy resins are reviewed and discussed in Chapter 4. These results are concerned with the use of carboxylic acid anhydrides, primary and secondary amines, dicyanodiamide, and imidazoles as curing agents. 

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