STRUCTURAL EPOXY ADHESIVES BASED ON HIGHLY BRANCHED POLY(AMIDOAMINE) CONTAINING CURING SYSTEM

摘要

Structural epoxy adhesives based on DGEBPA resins having high shear and peel strengths in combination of 80°C Tg, can be obtained using a novel cost effective curing system which contains HB PAMAM. To increase the Tg from 60°C, which was associated with DGEBPA epoxies having shear strength of 24 MPa and peel resistance of more than 9 N/mm, dimer acid modified epoxy was used. The targeted Tg of 80 C was obtained while preserving the high shear strength of 25 MPa (3500 psi) and sacrificing the peel resistance to a relatively high level of 4.7 N/mm (26 lbs./inch). Formulations that did not include about 20% of the HB PAMAM, containing the same epoxy resins, exhibited reduced shear, peel and Tg. The added value and synergy between the HB PAMAM containing curing system and the epoxy blend is evident and can lead to new cost effective structural epoxy adhesives. Additional work is planned to develop higher Tg formulations (above 80°C) based on HB PAMAMs possessing high peel and shear strengths, using a variety of tri and tetra functional epoxies.