Thermal Degradation and Kinetic Studies of New Flame-Retardant Phosphorus-Containing Polymers with Liquid Crystalline Properties

Abstract

In this study, two new thermotropic liquid crystalline phosphorus-containing polymers were prepared by polycondensation reaction of 1,4-phenylene-bis((6-oxido-6H-dibenz[c,e][1,2]oxaphosphorinyl)carbinol) with two different phosphonic dichlorides, namely ethyl dichlorophosphate and phenyl dichlorophosphate. The polymers were characterized by means of FT-IR, ¹H NMR, differential scanning calorimetry, polarized light microscopy, wide-angle X-ray diffraction, and thermogravimetric analysis. Thermogravimetric analysis was performed in nitrogen atmosphere by heating the samples over a range of temperatures from 25° to 700°C using five different heating rates. The kinetic processing of data was achieved using the Freeman-Carroll, ASTM E1641, and Kissinger methods.

Keywords:

• Kinetic analysis
• Polyphosphates
• Thermal stability
• Thermotropic LC polymers

Notes

^a Peak temperatures from DSC were taken as the phase transition temperature.

^b Phase transition temperature taken from PLM observation, first heating cycle at a heating rate of 10°C/min; K = solid, N = nematic phase, I = isotropic phase, LC = liquid crystalline phase.

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/gpac.