Interpenetrating Polymer Network (IPN) Adhesives for Electron Beam Cure

摘要

Electron beam (e-beam)-processed polymer adhesives have historically performed poorly compared to traditional adhesive technologies due to a lack of toughness engineered into these new types of adhesive materials. Consequently, sequential- and simultaneous-interpenetrating polymer networks (Seq-IPN and SIN) were developed and characterized. Seq-IPN adhesive pastes demonstrated exceptional lap-shear strengths (approaching 41 MPa) with glass transition temperatures (T sub g) of 100-120 deg. C. The sequential polymerization proceeds by first thermally curing the adhesive to the green-strength. The cure kinetics for the C-staged eq-IPNs have been investigated as a function of temperature and cure acceleration. SIN materials are being investigated to develop durable e- beam-curable film adhesives. The primary advantage of SIN film adhesives, compared to cationic e-beam systems, is insensitivity to surface contaminants (e.g., amine and water), which are known to hinder cure in cationic e-beam polymerization. Preliminary results have shown that the SIN e-beam adhesives have excellent properties. Lap-shear strengths exceeding 27.5 MPa with adhesive T sub g approaching 150 deg. C have been demonstrated on primed aluminum substrates. Structural, kinetic, and adhesive performance data for both seq-IPN and SIN structural adhesives cured by e-beam irradiation are presented.