Abstract

Diglycidyl ether of bisphenol A epoxy resin (DGEBA) was toughened with 5%, 10%and 15% (by wt) of caprolactam
blocked methylenediphenyl diisocyanate (CMDI)using 4,4‘- diaminodiphenylmethane (DDM) as curing agent. The
toughened epoxy resin was further modified with chemical modifier N, N‘-bismaleimido-4, 40-diphenylmethane
(BMI).Caprolactam blocked methylenediphenyl diisocyanate was synthesized by the reaction of caprolactam with
methylenediphenyl diisocyanate in presence of carbon tetrachloride under nitrogen atmosphere. Thermal properties of
the developed matrices were characterized by means of differential scanning calorimetry (DSC), thermo gravimetric
analysis (TGA), heat distortion temperature (HDT) and dynamic mechanical analysis (DMA). Mechanical properties
like tensile strength, flexural strength and impact strength were tested as per ASTM standards. The glass transition
temperature (Tg) and thermal stability were decreased with increase in the percentage incorporation of CMDI. The
thermomechanical properties of caprolactam blocked methylenediphenyl diisocyanate toughened epoxy resin were
increased by increasing the percentage incorporation of bismaleimide. The values of impact strength for epoxy resin
were increased with increase in the percentage concentration of CMDI. The homogeneous morphology of CMDI
toughened epoxy resin and bismaleimide modified CMDI toughened epoxy resin system was ascertained from scanning
electron microscope (SEM).

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