Fracture Toughness of a Silane Coupled Polymer-Metal Interface: Silane Concentration Effects

• Published in: The Journal of adhesion Vol. 81; no. 3-4; pp. 347 - 370
• Main Authors: Berry, Douglas H., Namkanisorn, Apinan
• Format: Journal Article
• Language: English
• Published: Basingstoke Taylor & Francis Group 01.03.2005; Taylor and Francis
• Subjects: Applied sciences; Exact sciences and technology; Forms of application and semi-finished materials; Fracture mechanics; Glassy polymers; Metals. Metallurgy; Nonmetallic coatings; Polymer industry, paints, wood; Polymer-metal adhesion; Production techniques; Sheets and films; Silane coupling agent; Surface treatment; Technology of polymers; Coating material; Fracture mechanics; Mechanical properties; Organic silane; Metal; Experimental study; Adhesion; Surface treatment; Coupling agent; Fracture toughness; Polymer-metal adhesion; Interface structure; Glassy polymer; Glassy polymers; Concentration effect; Styrene polymer; Formation mechanism; Silane coupling agent
• ISSN: 0021-8464; 1563-518X; 1545-5823
• DOI: 10.1080/00218460590944657

Fracture toughness of joints made from a glassy, 343,000 molecular weight polystyrene block bonded to chromic-sulfuric acid etched or phosphoric acid anodized aluminum are investigated. The fracture tests are performed with a 90-degree peel apparatus under "dry" laboratory conditions and "wet" conditions created by submerging the apparatus in a temperature controlled water bath. The bond strengths are controlled using various concentrations of styrl silane coupling agent added directly into the styrene monomer solution that polymerizes against the aluminum. Ellipsometric measurements on smooth silicon surfaces verify that the thickness of bound polymer is controlled by the silane to polystyrene mole ratio. X-ray photoelectron spectroscopy (XPS) analysis of fractured surfaces indicates that the fracture is near the aluminum surface. Both the wet and dry fracture energy as a function of bound polymer thickness on acid etched aluminum joints resemble quite closely the adhesion literature results obtained by fracturing pairs of fused, immiscible glassy polymers. Reasons for this similarity are discussed.