High-temperature matrix resins based on bispropargyl ethers (BPEs) - part 2: Curing kinetics of structurally diverse BPEs and their blends with bismaleimide

摘要

Structurally diverse bispropargyl ethers (BPEs) using resorcinol, quinol, 4,4'-dihydroxy biphenyl, bisphenol-A, 4,4'-dihy-droxy diphenyl ketone, 4,4'-dihydroxy diphenylsulphone, trimethyl indane bisphenol and tetramethyl spirobiindane bisphenol were synthesized, and it was separately blended with 4,4'-bismaleimido diphenyl methane (BMIM) in mole ratios (0.5:0.5). The structural characterizations of the materials are carried out using Fourier transform infrared and nuclear magnetic resonance studies. Differential scanning calorimetric analysis shows that the difference in the melting characteristics and decrease in the curing window for different BPEs were caused by the incorporation BMIM. Addition of BMIM to BPEs reduces the heat liberated during the thermal curing. The curing kinetics is investigated using Flynn-Wall-Ozawa, Vyazovkin and Friedman methods. Amongst the various BPEs investigated, the activation energy (E_a) values obtained from spirobiindane BPE (SPIPE) behaves entirely in a different manner compared to all other materials investigated. The apparent E_a values for SPIPE was observed to increase with increasing extent of reaction up to 0.2-0.5 and then the E_a values decrease with increasing extent of reaction up to 0.55-0.8. The E_a for the polymer blends obtained by the incorporation of BMIM with different BPEs shows nearly linear increase in the E_a value, and the rate of increase is influenced by the structure of the aromatic spacer present in between the propargyl groups.