Thermal degradation kinetics of structurally diverse poly(bispropargyl ethers-bismaleimide) blends

Abstract

Structurally diverse bispropargyl ethers using resorcinol, quinol, 4,4′-dihydroxy biphenyl, bisphenol-A, 4,4′- dihydroxy diphenyl ketone, 4,4′-dihydroxy diphenylsulphone, trimethyl indane bisphenol and tetramethyl spirobiindane bisphenol were prepared by using phase transfer catalyst. Synthesized materials were separately blended with 4,4′-bismaleimido diphenyl methane (BMIM) in mole ratios (0.5:0.5). The materials were thermally cured and the structural characterisation and the thermal properties of these cross-linked materials are investigated using Fourier-transform infrared (FTIR) spectrophotometer and thermogravimetric analyzer (TGA). Among the different materials investigated polyMRPE, polyMBPEBPA and polyMSPE show higher onset degradation temperature of 300 °C indicating higher thermal stability. The degradation kinetics is investigated using Flynn-Wall-Ozawa (FWO), Vyazovkin (VYZ) and Friedman (FRD) methods. Amongst the various cured materials investigated, the activation energy (Ea-D) values obtained for polyMRPE and polyMKPE were observed to increase continuously from α = 0.2 to 0.8 and the values range from 199 kJ/mol to 245 kJ/mol and 153 kJ/mol to 295 kJ/mol respectively. The crosslinked materials resulting from these bispropargyl monomers definitely need more energy for bond cleavage due to the presence of more aromatic units. The volatile products obtained during the thermal degradation of the polymers were analyzed using thermogravimetric-Fourier transform infrared analyses (TG-FTIR). The phenols, substituted phenols, carbon monoxide, carbon dioxide and small amount of aniline were found to be the major products during thermal degradation of these cured blends.