Epoxy resin Anhydride

Ph2-phen) in the cycloaliphatic epoxy (ERL-4221)/anhydride resin at 293 K. The electronic absorption spectrum ( ) of the uncured epoxy/anhydride resin without the incorporation of the organometallic complex is also shown. The excitation spectrum was recorded with emission monitored at 610 nm. (From Ref. 80.)... 

Figure 9 illustrates the dynamic moduli and complex viscosity results for the cycloaliphatic epoxy/anhydride resin. The tgei value denotes the time to gelation based on the dynamic moduli crossover (G = G") and is estimated at... 

The data shown in Tables II and III indicate the effectiveness of two of the phosphonium compounds as accelerators for epoxy-anhydride resins. From the data in Table II, it is noted... 

Phosphonium Latent Accelerators in Epoxy-Anhydride Resins... 

Table III. Viscosity (Storage) Data for Quaternary Phosphonixun Latent Accelerators in Epoxy-Anhydride Resins...

Latent Accelerator Concentration (% w/w) in Epoxy-Anhydride Resin (Days at 25 C) for Resin ... 

Table IV. Electrical Properties of Cured Epoxy-Anhydride Resins Containing Various Quaternary Phosphonium Compounds ...

Quaternary Arsonium and Stibonium Compounds. More recently, experimental work in this laboratory has revealed that quaternairy arsonium compounds (18) are extremely effective as latent accelerators for epoxy-anhydride resius. Surprisingly, it has also been found that quaternary stibonium compounds are very much less effective as accelerators than quaternary arsonium, phosphonium or ammonium compounds. In fact, the order of gelation reactivity of these compounds with epoxy-anhydride resins would appear to be as follows ... 

Quaternary phosphonium compounds have been found to be extremely effective latent accelerators for anhydride-cured epoxy resins employed in electrical insulation applications. Used at very low concentrations (0.01 to 0.25% level) in these resins, they have been found to give very fast gel times at elevated temperatures combined with very good storage stability properties at room temperature. Results show that the quaternary phosphonium compounds having non-halide anions give the best compromise of gel reactivity, storage stability and electrical properties. Comparison with other types of latent accelerators reveal that the quaternary phosphonium compounds are among the most effective additives yet discovered for epoxy-anhydride resin systems. 

FIGURE 4.11 Quasi-isothermal cure and vitrification of an epoxy-anhydride resin at 80°C at a frequency of l/60Hz. (From Van Assche, G., Van Mele, B., and Saruyama, Y., Thermochim. Acta, 377, 125, 2001. With permission.)... 

Var Varley, R. J., Tian, W. Toughening of an epoxy anhydride resin system using an epoxidized hyperbranched polymer. Polym. Intern. 53 (2004) 69-77. 

The experiment of Figure 2.2 will now be considered in more detail as a typical example of isothermal cure with vitrification. It shows the nonreversing heat flow (Figure 2.2a), the heat capacity (Figure 2.2b) and the heat flow phase (Figure 2.2c) as a function of reaction time for the quasi-isothermal cure of an epoxy-anhydride resin at 100°C for 200 min. The reaction exotherm obeys an auto-catalytic behaviour the heat flow increases at... 

Table 17. Isothermal curing times of aromatic isocyanate/epoxy and aliphatic epoxy/anhydride resin systems under conventional and microwave heating. Reprinted from (1999) Microwave heating and the acceleration of polymerization processes. In Wlochowicz (ed) Polymers and liquid crystals Proceedings of SPIE - The International Society for Optical Engineering, vol 2 [2] with permission ...

Table 19 Isothermal curing times of aromatic isocyanate/epoxy and aliphatic epoxy/anhydride resin systems under conventional and microwave heating...

Montserrat S, Malek J, Colomer P (1998) Thermal degradation kinetics of epoxy-anhydride resins I. influence of a silica filler. Thermochim Acta 313 83-95... 

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