Preparation of flame retardant polyamide 6/melamine cyanurate via in situ polymerisation and its characterisation

Polyamide 6 (PA6) is one of the principal thermoplastics used in the plastics engineering and textile industries. However, PA6 with low limiting oxygen index (LOI) burns easily and its melt drips will lead to spread of flames, which restricts its wider application in several areas. PA6/melamine cyanurate (MCA) composite was prepared via in situ polymerisation. Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis were used to characterise the chemical structure, thermal transitions and crystallinity and thermogravimetric behaviour of this synthetic flame retardant composite. The results showed that MCA/PA6 had higher crystallisation temperature than PA6 alone; the decomposition rate of MCA/PA6 was obviously lower than that of PA6. The UL-94 flammability test and LOI test revealed that the composite reached a UL-94 V-0 rating at 3·2 mm thickness and had a LOI value of 31·8% at a loading level of 8%MCA.