Development of a vegetable oil based plasticizer for preparing flame retardant poly(vinyl chloride) materials

Abstract

A novel method was developed to prepare a castor oil based flame retardant plasticizer containing phosphaphenanthrene groups (PCOPE) for the preparation of poly(vinyl chloride) (PVC). The molecular structure of PCOPE was characterized with FT-IR, ¹H NMR and ³¹P NMR spectroscopy. Flame retardant poly(vinyl chloride) materials were prepared via blending with PCOPE to substitute a petroleum-based plasticizer. The thermal stability and flame retardant performance of the PVC blends plasticized with different amounts of PCOPE were investigated by LOI, SEM, TGA, TGA-FTIR and cone calorimeter tests. The results showed that the plasticized PVC materials exhibited increased thermal stability and flame retardant performance. When all DOP was completely substituted with PCOPE in PVC blends, LOI value of the PVC materials increased from 23.6% to 36.7%, and the T_d, T₅₀, T_p1 and T_p1 values reached 289.4 °C, 318.2 °C, 293.8 °C and 444.3 °C, respectively. The pHRR value decreased from 379.0 kW m⁻² to 262.3 kW m⁻², whereas the av-HRR value decreased from 162.3 kW m⁻² to 108.4 kW m⁻². The THR value decreased from 31.8 MJ m⁻² to 17.9 MJ m⁻². This method provides a versatile way to prepare a bio-plasticizer from vegetable oils, and it is expected to partially or completely replace petroleum-based plasticizers in the manufacture of PVC materials.