Curing Kinetics and Thermal Properties of Aromatic Multifunctional Epoxy Resins

Abstract

In order to investigate the relationship between the chemical structure of multifunctional epoxy resins and their properties, two tetrafunctional epoxies with different aromatic rings content in the molecular main chain, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether (4,4'-TGDDE) and N,N,N',N'-tetraglycidyl-2,2-bis[4-(4-aminophenoxy)phenyl]propane (TGBAPP), were cured with 4,4'-diaminodiphenyl ether (4,4'-DDE) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), respectively. Then four amine curing systems (TGBAPP/BAPP, TGBAPP/4,4'-DDE, 4,4'-TGDDE/BAPP and 4,4'-TGDDE/4,4'-DDE) were obtained. Additionally, the 4,4'-TGDDE and another TGDDE with m-glycidyl amino, named N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether (3,4'-TGDDE) were cured with methyl nadic anhydride (MNA). Then the anhydride curing systems (4,4'-TGDDE/MNA and 3,4'-TGDDE/MNA) were prepared. The curing kinetics and thermal properties of these systems were studied in detail. The results indicated that the anhydride curing systems exhibited higher curing reactivity than the amine curing systems, and the resins cured with the anhydride showed better thermal properties. Moreover, introducing more aromatic rings into the backbone would decrease the curing reactivity but enhance the thermal property of the multifunctional epoxy resins. And the tetrafunctional epoxy with p-glycidy amino groups had higher curing reactivity than the epoxy with p-glycidy amino groups, and the thermal property of the front epoxy was better.

Effect of aromatic substitution on the cure reaction and network properties of anhydride cured triphenyl ether tetraglycidyl epoxy resins

“…This is supported by the dynamic DSC results also in Table , which indicate that T p , the temperature at the peak rate of reaction, decreases consistently with increasing para substitution, again regardless of hardener, indicating a faster cure reaction. Support for these results comes from Yu et al using a related tetrafunctional amino glycidyl epoxy resin cured with MNA who also reported a modest increase in reaction rate as aromatic substitution changed from meta to para. The total enthalpies during cure, both dynamic and isothermal in Table reveal an overall decrease in enthalpy with increasing para substitution regardless of hardener.…”

“…Patel et al synthesized novel tetrafunctional epoxy resins consisting of four aromatic rings linked via two ether groups and different central groups such as phenyl, isopropyl, and cyclo‐hexyl but mostly compared the effect of different hardeners rather than the impact of the structural variation of the epoxy resin on the properties. Yu et al also explored the synthesis and cure of a similar four membered tetrafunctional epoxy resin with two ether links and a central isopropyl group, with both aromatic amine and anhydride hardeners. They concluded that introducing more aromatic rings decreased the rate of cure but enhanced thermal properties.…”

“…Another approach has been to synthesize multiaromatic epoxy resins, consisting of either three or four aromatic rings linked together via some flexible spacer group. 18 Patel et al [19][20][21] synthesized novel tetrafunctional epoxy resins consisting of four aromatic rings linked via two ether groups and different central groups such as phenyl, isopropyl, and cyclo-hexyl but mostly compared the effect of different hardeners rather than the impact of the structural variation of the epoxy resin on the properties. Yu et al 18 also explored the synthesis and cure of a similar four membered tetrafunctional epoxy resin with two ether links and a central isopropyl group, with both aromatic amine and anhydride hardeners.…”

The synthesis of a secondary branched epoxy‐modified silicone resin and its application at low temperature

“…Multifunctional epoxy resins contain three or more epoxy groups, which are incorporated into the epoxycured system by reaction with the curing agent. [18][19][20][21] Multifunctional epoxy resins are mainly used as modifiers and matrix resins to obtain cured epoxy resin products with special properties, such as higher mechanical properties, glass transition temperature (T g ) value, heat resistance, and dielectric properties. Thomas et al [22][23][24] reported a series of biobased thermoset epoxides, such as acid-cured norbornylized seed oil epoxides, new epoxidized vegetable oils-based thermosets, biobased methacrylate epoxidized-thermosets, and so on.…”

“…Multifunctional epoxy resins contain three or more epoxy groups, which are incorporated into the epoxy‐cured system by reaction with the curing agent 18–21 . Multifunctional epoxy resins are mainly used as modifiers and matrix resins to obtain cured epoxy resin products with special properties, such as higher mechanical properties, glass transition temperature ( T g ) value, heat resistance, and dielectric properties.…”