Cover Image, Volume 138, Issue 33

Abstract

Yanqin Shi and colleagues prepared one kind of highly efficient compound antibacterial agents by grafting green natural organic antibacterial agents to (3‐aminopropyl) triethoxysilane modified zinc oxide sheets. The polypropylene composites with the compound antibacterial agents have excellent antibacterial effect on both the Escherichia coli and Staphylococcus aureus, due to the double synergistic antibacterial effects. Meanwhile, the compound antibacterial agents have excellent migration resistance. DOI: https://doi.org/10.1002/app.50911

Synthesis of cyclotriphosphazene‐containing imidazole as a thermally latent hardener for epoxy resins and its application in carbon fiber reinforced composites

“…In sharp contrast, the pot lives of epoxy systems containing 1.27, 3.80, and 6.33 wt% CPI are prolonged to 17, 14, and 13 days, respectively. It should be noted that although 2MI has the reactive hydrogen on the 1‐position nitrogen atom, it was reported that this reactive hydrogen seemed to have less effect on the thermal latency of imidazole hardeners 43 . Representatively, the epoxy system containing 3.00 wt% 2MI will completely lose fluidity in 2 days, whereas the epoxy system containing 3.80 wt% CPI can maintain fluidity after 18 days (Figure 5c).…”

“…It should be noted that although 2MI has the reactive hydrogen on the 1-position nitrogen atom, it was reported that this reactive hydrogen seemed to have less effect on the thermal latency of imidazole hardeners. 43 Representatively, the epoxy system containing 3.00 wt% 2MI will completely lose fluidity in 2 days, whereas the epoxy system containing 3.80 wt% CPI can maintain fluidity after 18 days (Figure 5c). In addition, because of the high viscosity at room temperature, uncured epoxy systems are generally used under heating conditions to improve their processability.…”

“…24 Besides, introducing substituent groups to the secondary amine ( NH) of the imidazole ring is also an effective approach to prepare latent imidazole hardeners owing to the steric hindrance effect. 4,12,[25][26][27] If the introduced substituent groups can reduce the nucleophilicity of the imidazole moiety through the electron-withdrawing effect, the curing reactivity of imidazole hardeners would be reduced, resulting in improved latency. 10 For instance, Yang et al 25 introduced the s-triazine ring to the 1-position nitrogen of the imidazole ring.…”