Properties of epoxy resins cured with ring-alkylated m-phenylene diamine blends

Diglycidyl ether of bisphenol-A was cured, individually, with diaminoisopropyl benzene (DAIPB), diaminoethyl benzene (DAEB), blends of DAIPB/DAEB (up to 40 wt% DAEB), and DAIPB modified with up to 5 wt% amine-terminated poly(butadiene-co-acrylonitrile) liquid rubber (ATBN). For each diamine system glass transition temperature (differential scanning calorimetry) and room temperature tensile properties (Instron) were determined. Blends of DAIPB/DAEB produced cured resins displaying greatly increased tensile strength (up to 50% higher) and slightly lower glass transition temperature compared with resins cured with either diamine alone. DAIPB modified with ATBN yielded moderately improved tensile properties over DAIPB alone. Blends of DAIPB/DAEB (from 10 to 40 wt% DAEB) were observed to be eutectic liquids at room temperature.