Release Behavior of Benzimidazole-Intercalated α-Zirconium Phosphate as a Latent Thermal Initiator in the Reaction of Epoxy Resin

Abstract

The intercalation compound of benzimidazole with α-zirconium phosphate (α-ZrP) was evaluated as a latent thermal initiator in the reaction of glycidyl phenyl ether (GPE) and hexahydro-4-methylphthalic anhydride (MHHPA). No reaction occurred at 60 °C after 1 h. Upon increasing the temperature to 140 °C, the conversion reached 97% after 1 h. The deintercalation ratio of Bim from the intercalation compound of benzimidazole with α-zirconium phosphate (α-ZrP·Bim) was measured in the reaction of the GPE-MHHPA system. The deintercalation ratio increased upon increasing the temperature, reaching 97% at 120 °C after 1 h. The storage stability at 25 °C and 40 °C in the reaction of GPE-MHHPA was tested and was found to be maintained for 14 days at 25 °C. The intercalation compound of α-ZrP·Bim can effectively serve as a latent thermal initiator in the reaction of GPE-MHHPA.

Latent Curing, Chemorheological, Kinetic, and Thermal Behaviors of Epoxy Resin Matrix for Prepregs

“…As reported in the literature on epoxy/CF prepregs, the guaranteed shelf life at −18 °C is at least six months and that at 23 °C the service life is 10 days. 49 In this study, an accelerated condition (60 °C and 1 day) 42 was set to evaluate storage stability in a shorter period. Under this aging environment, the exothermic enthalpy (ΔH) of EM/D4/T1 during curing substantially decreased and its glass transition temperature (T g ) increased because of curing reactions during the storage.…”

“…To avoid the precuring behavior of epoxy resins, high temperature curable epoxy systems composed of anhydride or diacid can be employed. , However, a catalyst or accelerator is routinely used due to their extremely high exothermic reaction peak temperature (>300 °C). , The even small concentration of catalyst/accelerator for the epoxy–anhydride and epoxy–diacid systems brings about unstable reactive behaviors at room temperature. To solve these issues, three latent curing strategies can be harnessed, namely, (1) latent curing agent, (2) encapsulation, and (3) phosphorus-based complex compound. − As an example, imidazole-based hardeners were coated by a polymer shell . The polymer shell in core–shell particles composed of polymer and hardener was stable below the glass transition temperature or melting temperature of the polymer.…”

Temperature-Dependent Enhancement Effects for TBD (1,5,7-Triazabicyclo[4.4.0]dec-5-ene) with 2-Methylimidazole-Intercalated α-Zirconium Phosphate as a Latent Thermal Initiator in the Reaction of Glycidyl Phenyl Ether

“…The %conversion values for GPE with TBD for a 1 h reaction over the temperature range 60 to 120 • C are shown in Figure 1b, and it is clear that the polymerization reaction did not proceed under the specified conditions. performance as latent thermal initiators in the reaction of GPE with hexahydro-4-methylphthalic anhydride (MHHPA) [13][14][15][16]. However, it is important to develop a highly active latent initiating system to avoid the need for high-temperature curing.…”

“…We have previously reported that primary alkylamines intercalated with α-zirconium phosphate (α-ZrP) may serve as latent thermal initiators in the reaction of glycidyl phenyl ether (GPE) [11,12], and that the compounds 1,4-diazabicyclo [2,2,2] with hexahydro-4-methylphthalic anhydride (MHHPA) [13][14][15][16]. However, it is important to develop a highly active latent initiating system to avoid the need for high-temperature curing.…”

Acceleration effects of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene with 2‐methylimidazole‐intercalated α‐zirconium phosphate as a latent thermal initiator in the reaction of glycidyl phenyl ether and hexahydro‐4‐methylphthalic anhydride

“…We have previously reported that primary alkylamines intercalated with α‐zirconium phosphate (α‐ZrP) may serve as latent thermal initiators in the reaction of glycidyl phenyl ether (GPE) and that intercalation compounds of 1,4‐diazabicyclo[2,2,2]octane (DABCO), 1,8‐diazabicyclo[5,4,0]undec‐7‐ene (DBU), imidazole (Im), 2‐methylimidazole (2MIm), 2‐ethyl‐4‐methylimidazole (2E4MIm), and benzimidazole (Bim) intercalated with α‐ZrP show good performance as latent thermal initiators in the reaction of GPE with hexahydro‐4‐methylphthalic anhydride (MHHPA) . Latent thermal initiators of imidazoles have been developed for curing of epoxy resins .…”