Abstract
The authors studied the influence of melamine polyphosphate flame-retardant (MPP-FR) and glass fibre on the non-isothermal crystallisation behaviour of a polyamide (PA66) by differential scanning calorimetry (DSC). The glass fibre reinforced PA66 (PA66/GF) and its reinforced flame retarded equivalent (PA66/GF/FR) were prepared using a twin-screw extruder. The experimental results demonstrated that the MPP-FR increased the crystallisation rate and decreased the supercooling required for crystallising nucleation. The glass fibres increased the crystallisation rate and the amount of supercooling.
Avrami analysis showed that the non-isothermal crystallisation of PA66 and its composites followed the Avrami equation. The activation energy for the transport of macromolecular segments to the growing surface was calculated by using the Kissinger method based upon DSC data, and the calculated activation energies were 243.5 kJ·mol−1, 201.1 kJ·mol−1 and 305.9 kJ·mol−1 for PA66, PA66/GF and PA66/GF/FR, respectively. The activity of nucleation for GF and MPP-FR were 0.87 and 0.79 respectively, calculated by Dobreva's method. The results indicate that the MPP-FR has more effective ability to promote heterogeneous nucleation than GF.