A comparative study of the preparation and characterization of aromatic and aliphatic bismaleimides to produce modified siliconized epoxy intercrosslinked matrices for engineering applications

A novel hybrid intercrosslinked network of hydroxyl-terminated polydimethylsiloxane modified epoxy and bismaleimides [N,N'-bismaleimido-4,4'-diphenylmethane and 1,6-bis(maleimido)hexane] matrix systems were developed. Epoxy resin was modified with 5, 10, and 15% (wt%) of hydroxyl-terminated polydimethylsiloxane using gamma -aminopropyltriethoxysilane as crosslinking agent and dibutyltindilaurate as catalyst. The reaction between hydroxyl-terminated polydimethylsiloxane and epoxy resin was confirmed by IR spectral studies. The siliconized epoxy systems were further modified with 5, 10, and 15% (wt%) of both aromatic and aliphatic bismaleimides separately. The castings and E-glass fiber-reinforced composites prepared were characterized for their mechanical properties. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of the matrix samples were also performed to determine the glass transition temperature (T-g) and thermal degradation temperature of the hybrid intercrosslinked systems. Data obtained from mechanical studies and thermal characterization indicate that the introduction of siloxane into epoxy resin improves the toughness and thermal stability, with reduction in strength and modulus values. The incorporation of aromatic bismaleimide into epoxy resin improved both tensile strength and thermal properties, whereas it was observed that the incorporation up to 5%, of aliphatic bismaleimide into epoxy resin decreased the stress-strain value and above 5%, increased the strength properties. However, the introduction of both aromatic and aliphatic bismaleimides (aromatic and aliphatic) into siliconized epoxy resin influenced both mechanical and thermal properties according to the percentage content.