Solid state shear compounding to prepare flame retarded polyamide 6/melamine cyanurate

In this study, a novel technology, solid state shear compounding (S³C) carried out at ambient temperature with pan-mill type equipment, was used to prepare composite powders of polyamide 6/melamine cyanurate (PA6/MCA). The prepared powder of high melt flow index can be used as a flame retardant master batch loaded into PA6, or directly moulded into flame retarded PA6 samples. This technology resolves the limitations of conventional melt compounding in extruders by overcoming the decomposition of flame retardants at high temperatures and the phase segregation caused by thermodynamic incompatibility between flame retardant and polymer, as well as the baffle of viscous polymer melts on the dispersion of flame retardant particles in the melt compounding process, yielding an ideal mix and dispersion of MCA in PA6. Additionally, the S³C process can also provide chemical interaction between MCA and PA6 macromolecular chains, and yield in situ compatibilisation effects. During this study, it was found that the flame retarded PA6 formed by the S³C process has improved flame retarding efficiency, and the loading level of flame retardant is greatly reduced while maintaining the desired flame retardancy.