Studies on the adhesive properties of solid elastomer-modified novolac epoxy resin

Adhesive properties like lag shear strength and T-peel strength of novolac epoxy resin modified with carboxyl terminated butadiene acrylonitrile (CTBN ) solid resin and cured with two different curing agents namely, dicyandiam ide (DICY) and 3,3'-diaminodiphenyl sulphone (DDS) were evaluated using alu minium adherends. Substantial improvement in adhesive properties was obtain ed by the inclusion of moderate concentrations of CTBN in the formulations. Adhesive properties of the formulations were evaluated when used as paste, nylon-carrier supported and unsupported film adhesives. Optimum concentrat ions of 20 parts by weight (pbw) and 25 pbw of solid CTBN in epoxy were obt ained for the DICY and DDS cured systems, respectively. Inclusions of large r amounts of CTBN led to flexibilisation of the systems thereby reducing th e adhesive properties. CTBN also reduced the glass transition temperatures and high-temperature strength retention of both the systems. The developmen t of two-phase morphology for the CTBN-modified systems was evident from sc anning electron micrographs(SEM). (C) 2000 Elsevier Science Ltd. All rights reserved.