Design of Poly(cyclotriphosphazene)-Functionalized Zirconium Phosphate Nanoplatelets To Simultaneously Enhance the Dynamic Mechanical and Flame Retardancy Properties of Polyamide 6

Kuruma Malkappa; Jayita Bandyopadhyay; Suprakas Sinha Ray

doi:10.1021/acsomega.0c01247

Design of Poly(cyclotriphosphazene)-Functionalized Zirconium Phosphate Nanoplatelets To Simultaneously Enhance the Dynamic Mechanical and Flame Retardancy Properties of Polyamide 6

ACS Omega. 2020 Jun 1;5(23):13867-13877. doi: 10.1021/acsomega.0c01247. eCollection 2020 Jun 16.

Authors

Kuruma Malkappa¹, Jayita Bandyopadhyay¹, Suprakas Sinha Ray^{1

2}

Affiliations

¹ Centre for Nanostructures and Advanced Materials, DSI-CSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research, Pretoria 0001, South Africa.
² Department of Chemical Sciences, University of Johannesburg, Doorfontein, Johannesburg 2028, South Africa.

Abstract

To obtain polyamide 6 (PA6) composites with improved flame retardancy and thermomechanical properties, highly cross-linked supramolecular poly(cyclotriphosphazene)-functionalized α-zirconium phosphate (f-ZrP) nanoplatelets were synthesized and melt-blended with PA6 in a twin-screw extruder. The performance enhancements of composites were investigated through measuring the dynamic mechanical property and observing cone calorimeter data, toxic gas evolution, and UL-94 rating. The thermomechanical performance of PA6 was increased by 37.2% after composite formation with f-ZrP. As for the fire retardancy performance, compared to neat PA6, the composite containing 10 wt % f-ZrP showed 41.7 and 30.4% decrease in the peak heat and total heat release rates, respectively, and the UL-94 rating of the composite was V-0. Moreover, the thermogravimetric analysis combined with infrared spectroscopy revealed that the addition of f-ZrP to the PA6 led to decrease in the evolution of the volatile compounds and toxic gases, with the formation of highly cross-linked P-N-containing dense char with microspheres, providing a strong barrier to the inhibition of the heat and flammable volatile components transferring between the flame zone area and substrate during the combustion test. Finally, based on the obtained results, the possible mechanisms for improved mechanical and fire retardancy properties of the composites were proposed.