Epoxy/epoxies thermal decomposition

Thermal decomposition of the matrix material offers a simple way of recovering the relatively expensive reinforcing fibres from a fibre-reinforced laminate. The epoxy resin matrix was made to decompose by thermal treatment in air or nitrogen, this treatment allowing the carbon fibres to be recovered without damage. 

Persistent photosensitivity developed in eight men after occupational exposure to hot epoxy resin fiimes. The condition was limited to sites contacted by the resin. Small doses of ultraviolet-A light evoked abnormal reactions consisting of erythema, edema, and papules in the clinically involved skin. Positive photopatch tests were observed to epoxy resin in four subjects and to bisphenol A in all subjects. Another study showed that bisphenol A can be released during the thermal decomposition of epoxy resin in the temperature range of 250-350°C. Photosensitizing activity was explained by the formation of ftee radicals during exposure to ultraviolet-B radiation of bisphenol A vapor, to form a semiquinone derivative of bisphenol A ... 

Simultaneous TGA and DTA were used by Maycock et al. to study the kinetics of the isothermal and adiabatic thermal decomposition of 8-HMX (one of the polymorphs of HMX) under helium atmosphere and reported activation energy [44] —63 KcalmoT1. The use of simultaneous DTA/TG has been reported for compatibility testing of TNT with two epoxy-and two alkyd resins paints [21, 45]. 

A recent oommtiruo tion by Gritter and Wallace discloses initiation of a study of the free-radical chemistry of epoxides Under the influence of U t-butoxy radicals, formed by thermal decomposition of di-lerf-butyl peroxide, propylene oxide is believed to yield an epoxy radical as shown in Eq. (3). The latter undergoes Isomerization to CHsCOCH - and further reaction with unreaoted propylene oxide or other available substrates, such as 1-octene, toluene, oyolohexene, and ethanol,fl7a as shown in Eq. (3). 

A large exothermal effect resulting from chemical reactions is typical of these processes. When using oligomeric initial components, for example, formulations based on urethane prepolymers, epoxy resins, and lactams, self-heating may cause thermal decomposition. For this reason the correct choice of the initial solidification temperature is very important. 

Levchik, S. V., Camino, G., Luda, M. P., Costa, L., Muller, G., and Costes, B., Epoxy resins cured with aminophenymethylphosphine oxide Mechanism of thermal decomposition, Polym. Degrad. Stab., 1998, 60, 169-183. 

The overwhelming majority of foams are TPs, but TSs are also foamed with CBAs, although some of them do create problems. Popular TS foams are made from polyurethane, polyester, phenolic, epoxy, and rubber. Thermal decomposition of the blowing agent with certain plastics such as TS polyesters cannot be applied in this system because the heat of polymerization is not high enough to induce decomposition. But chemical reactions simultaneously produce gas and free radicals they typically involve oxidation and reduction of a hydrazine derivative and peroxide. The reactions are catalyzed by metals, which can be used repeatedly. 

Tseng et al. (51) reported the epoxy nanocomposites in which the nanotubes were functionalized by maleic anhydride by using plasma treatment. The thermal decomposition temperature was reported to increase with increasing the extent of the nanotubes in the composites as shown in Figure 2.16a. Untreated nanotubes were also used to reinforce the polymer and the increase in the decomposition temperature was also observed in this system as a function of filler content, but the enhancement was more significant using the functionalized nanotubes. This was attributed to... 

Electrical and electronic devices are made utilizing several various types of plastic materials, thus when discarded their waste is difficult to recycle. The plastics employed in housing and other appliances are more or less homogeneous materials (among others PP, PVC, PS, HIPS, ABS, SAN, Nylon 6,6, the pyrolysis liquids of which have been discussed above). However, metals are embedded in printed circuit boards, switches, junctions and insulated wires, moreover these parts contain fire retardants in addition to support and filler materials. Pyrolysis is a suitable way to remove plastics smoothly from embedded metals in electrical and electronic waste (EEW), in addition the thermal decomposition products of the plastics may serve as feedstock or fuel. PVC, PBT, Nylon 6,6, polycarbonate (PC), polyphenylene ether (PPO), epoxy and phenolic resins occur in these metal-containing parts of EEW. 

Eelix, D., Schreiber, J., Piers, K., Horn, U., Eschenmoser, A. New version of epoxy ketone-> alkynone fragmentation. Thermal decomposition of hydrazones from a,P-epoxycarbonyl compounds and W-aminoaziridines. Helv. Chim. Acta 1968, 51, 1461-1465. 

The thermal decomposition of the brominated epoxy resin depicted in Figure 6 occurs in the following manner (Figure 7). 

Several Co2 +, Sn2 +, Pr3 +, Cu2 +, Cu1 +, and Fe3+ compounds were used for flame retardation of epoxy-based polymers 176). Zarkhina et al.177) have shown that Mn2 +, Cr3 + and Ce3 + compounds reduce the temperature of initiation of the thermooxidative decomposition of the same polymer by 80-100 °C, but the rate of the decomposition itself is lower than that of the unmodified polymer. Thermogravimetric and differential thermal analysis have shown that Men+ have no influence on the thermal decomposition of the polymer in the absence of an oxidative atmosphere. 

Foaming with dry gases generated by the thermal decomposition of a dihydro-oxadiazinone + azodicarboxylic acid amide or ester PPE-polyolefin graft copolymer and NBR Epoxy-terminated liquid PB, with either PP-MA or SEBS SBR and SBS copolymer ABS and SAN Hydroxynaphthoic acid... 

Recent work in the area has concentrated on the reactions of carotenoids with peroxyl radicals, generated mainly by the thermal decomposition of azo-initiators that lead to a variety of products. " Most of these products seem to be apocarotenals or apocarotenons of various chain lengths produced by cleavage of a double bond in the polyene chain, such as P-apo-12 -carotenal, P-apo-14 -carotenal, P-apo-lO-carotenal, and P-apo-13-carolenone. Kennedy and Liebler " reported that 5,6-epoxy-p,p-carotene and 15,15 -epoxy-P,P-carotene and several unidentified polar products were formed by the peroxyl radical oxidation of P-carotene by the peroxyl radicals. 

BSH is used for foaming rubbers, polystyrene, epoxy resins, polyamides, PVC, polyesters, phenol-formaldehyde resins, and polyolefins. However, the thermal decomposition of BSH yields not only nitrogen but also a nontoxic residue (disulfide and thiosulfone) which may degrade to give thiophenol and thus an unpleasant odor to the foams. 

Levchik SV, Weil ED. Thermal decomposition, combustion and flame retaidancy of epoxy resins - a review of recent literature. Polymer International. 2004 53(12) 1901-1929. 

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