Preparation and properties of halogen-free flame-retardant layered silicate-polyamide 66 nanocomposites

The relationship between the morphology, flammability and mechanical properties of layered silicate-polyamide 66 (PA66) nanocomposites was investigated. The nanocomposites were composed of PA66, melamine-modified layered silicate (MLS) as a nanofiller, and/or melamine cyanurate (MC). Samples of MLS with different dispersion states were obtained by changing the melt-mixing procedures for PA66, MLS and MC. X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal analysis, strength tests, cone calorimetry tests and UL 94 vertical burning tests were used to examine the effects of MLS on the morphology, mechanical properties and flame resistance performance of the materials. The data revealed a correlation between the dispersion state of the MLS layers and flame retardancy. The nanocomposite manufactured by one-stage kneading of a mixture of PA66, MLS and MC earned a UL 94 rating of V0. The flame retardancy of dripping particles during combustion was found to be due to uneven dispersion of MLS in the PA66 matrix.