Facile Synthesis of Melamine/G-C3N4 Covalent Organic Framework (COF) by Indirect Intercalation and Its Flame Retardant

In this paper, a covalent organic framework (COF) based on g-C3N4 was designed firstly. The COF is arranged through an indirect interrelation method among melamine and g-C3N4. During the reaction, Cu2+ was used to expand the layer space of g-C3N4. The as-prepared COF were characterized by SEM, TEM, FTIR, and XRD. The obtained product is a melamine interrelation g-C3N4 composite material (MCN) with COF structure. The MCN was used as flame retardant for cable sheath material. The thermal stability, thermal shrinkage, oxygen record and vertical burning of link sheath material contain MCN were tested. The results showed that the MCN flame retardant increases the thermal stability time of the sheath material from 89 min to 131 min, and the thermal shrinkage rate diminished from 4.17% to 2.00%. The LOI is 29.5, and the flame retardant grade reaches UL-94 V-0. The SEM analysis of the carbon residue of the cable sheath material after burning, it was found that the state of the carbon layer of the link sheath material transform into a thick honeycomb structure by the impact of the MCN flame retardant, which forestalls the dispersion of oxygen and burnable gases, in this way hindering the transmission of flame.