Influence of Aniline Addition on the Cure, Mechanical Properties and Water Absorption Characteristics of Amine Cured Epoxy Resins

Abstract Curing, dielectric, gravimetric, dynamic mechanical, infrared and density measurements are reported on the effect of the incorporation of mono and bi-functional amines on the water absorption and mechanical properties of diglycidyl ether of bisphenol A (DGEBA), MY720 (Ciba Geigy) cured with diaminodiphenylmethane, (DDM), HT972, (Ciba Geigy) and diaminodiphenylsulphone, (DDS), HT976, (Ciba Geigy). Resin samples were prepared with incorporation of mono/bi-functional amines of different ratios from 0% through to 60%. Analysis of these materials showed little difference in the water uptake properties of DGEBA cured with DDM than with DGEBA cured with DDS. The DDS cured material showed slightly better resistance to water uptake with a reduced water uptake and diffusion coefficient. The addition of aniline and N-ethylaniline increased the cure time of the resin due to hindrance of the network formation. Gravimetric water absorption measurements showed an increase in the diffusion coefficient and equilibrium water content on addition of N-ethylaniline due to more free volume in the system as confirmed by dynamic mechanical results. Addition of aniline showed an initial increase in the diffusion coefficient and then a decrease at greater than 20% aniline which is reflected by a corresponding increase in the glass transition temperature as shown by dynamic mechanical measurements. Key Words: Epoxy resinanilinecuremechanical propertieswater absorption