Modified magnesium hydroxide encapsulated by melamine cyanurate in flame-retardant polyamide-6

In this paper, a novel modified magnesium hydroxide (MH) was successfully prepared with gamma-(2,3-epoxypropoxy)propyl trimethoxysilane (KH-560) via the wet process. The optimum modification conditions were obtained as follows: KH-560 dosage of 1.0 wt% at 80 degrees C for 2 h. The modified MH encapsulated by melamine cyanurate (MCA) at the mass ratio was 1:3. Using polyamide-6 (PA6) as matrix, MCA-MH as flame retardant, a series of flame-retardant PA6/MCA-MH composites were prepared by melt blending and injection molding. The flame retardancy, thermal property, and mechanical properties of PA6/MCA-MH composites were investigated. The investigation results showed that MCA-MH could effectively suppress the melt-dipping behavior and reinforce flame retardancy of PA6. PA6/MCA-MH composites successfully passed the vertical combustion (UL-94) V-0 rating and limiting oxygen index (LOI) as high as 32.5% with the incorporation of 20 wt% of MCA-MH. The residues of the PA6/MCA-MH composites were increased with the increasing MCA-MH. What's more, the mechanical properties of the composites were also enhanced because of MCA-MH had better compatibility and dispersion in the PA6 matrix compared with MH. Therefore, PA6/MCA-MH composites with excellent flame retardancy while have maintained optimal mechanical properties can be obtained.