Structure and Properties of Polymer Interphases.
Abstract
The structure of polymer interphases in adhesive joints has been determined using x-ray photoelectron spectroscopy and internal reflection infrared spectroscopy. When an epoxy adhesive was cured against 2024 aluminum using a polyamine curing agent, the amount of crosslinking in the adhesive adjacent to the oxide was significantly higher than in the bulk adhesive due to catalysis of the curing reaction by hydroxyl groups present on the oxidized surface of the aluminum and to protonation of the amino groups on the polyamine curing agent. When an epoxy adhesive was cured against titanium that had been pre-treated with dilute aqueous solution of gamma-aminopropyltriethoxysilane gamma-APS), the structure of the interphase depended on the curing agent. With tertiary amine salt curing agents, there was little interdiffusion of the silane and the epoxy and the interphase consisted mostly of a siloxane polymer. When anhydride curing agents were used, there was considerable interdiffusion of the silane and the epoxy and the silane reacted with the curing agent to form an interphase that contained amide and a few imide groups. Metal substrates were found to have a significant effect on the structure of the silane primer. When gamma-APS films were deposited on iron or titanium and then dried at 110 C, the silane polymerized to form siloxane polymers. The amino groups in the siloxane polymers absorted carbon dioxide and water from the atmosphere to form amine bicarbonates salts.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1986
- Accession Number
- ADA176325
Entities
People
- F. James Boerio
Organizations
- University of Cincinnati