DIGLYCIDYL BIPHENYLPHOSPHATE BASED FLAME RETARDANT LIQUID CRYSTALLINE THERMOSETS

Abstract

Flame retardant liquid crystalline thermosets (FR‐LCTs) were synthesized from diglycidyl biphenylphosphate (DGBP), with various aromatic diamines namely, 2,5‐bis(p‐aminophenyl)‐1,3,4‐oxadiazole, 4,4′‐diaminodiphenyl sulphone, 4,4′‐ diaminodiphenyl methane, and biphenyldiamine. Cure kinetics and mesomorphic behavior of DGBP/diamine mixtures were performed on differential scanning calorimetry and hot stage optical microscope. Mechanical and cross‐linking properties of cured LCTs were characterized by dynamic mechanical analysis. The DGBP/diphenyldiamine combination exhibited high modulus and Tg values attributed to presence of more local order. The thermogravimetric analysis revealed that the LCTs were stable in the range 278–297°C with >43 Limiting Oxygen Index (LOI) values.

Keywords:

• Cure kinetics
• Dynamic mechanical analysis
• Flame retardant
• Liquid crystalline thermoset

ACKNOWLEDGMENT

We gratefully acknowledge the financial support provided for this research work by Department of Science and Technology (Ref. Sanction No. SR/S1/PC‐14/2003), New Delhi, India, under the SERC Scheme.