Dillingham G.,Brighton Technologies Group, Inc
Annual Technical Conference - ANTEC, Conference Proceedings | Year: 2013
Surface treatments of metals and polymers are frequently necessary to control properties such as adhesion of paints and sealants. Because surface properties are determined by only the uppermost few molecular layers, measuring these properties in manufacturing environments can be challenging. Water contact angles can be obtained very rapidly and conveniently and provide sensitive, quantitative feedback of surface properties important for adhesion.
Dillingham G.,Brighton Technologies Group, Inc
Technical Paper - Society of Manufacturing Engineers | Year: 2014
The fundamental relationships between surface chemistry, surface morphology, and adhesion are briefly reviewed. The effect of typical metal and composite surface preparation processes on these surface properties is discussed. The use of wetting measurements to determine these properties and their ability to quantitatively predict failure mode and strength of adhesive/adherend interfaces is described. Industrial examples of these measurements are presented.
Giles Dillingham R.,Brighton Technologies Group, Inc
International SAMPE Technical Conference | Year: 2013
A primary consideration in adhesive bonding of composites is to create bonded structures that have predictable strength. The cohesive strengths of adhesives and composites are well understood and highly predictable. However, interfacial strength is a complex function of the interaction of the adhesive with the prepared substrate surface, and can be difficult to predict. For this reason interfacial failure is unacceptable, and failure mode may be a more important characteristic of composite-composite adhesive bonds than the ultimate strength. A somewhat weaker bond that always fails cohesively with a highly predictable failure load may be preferable to a stronger bond that fails interfacially on occasion due to poorly controlled surface treatment variables. Because of this, processes used to prepare a composite surface for bonding must be well understood and highly reproducible. This paper discusses the relationship between surface composition and failure mode, and demonstrates how conceptually simple measurements of the wetting properties of the surface with an inert probe fluid can be an excellent predictor of failure mode in bonded structures. Copyright 2013 by Aurora Flight Sciences.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 978.23K | Year: 2006
Surface energy is potentially the most critical predictor of performance for composite/composite adhesive bonds. It is straightforward to measure the surface energy of a planar composite using, for example, contact angle measurements obtained from a range of probe liquids. However, once a surface has been roughened on a microscopic scale by a process such as grit blasting, quantifying the surface energy becomes a much more difficult task. In Phase I it was demonstrated that the wetting behavior of a single carefully chosen probe liquid is an excellent predictor of subsequent adhesive bond performance, even on a highly roughened surface. It was further demonstrated that the probe liquid wetting behavior was well quantified by measuring the diameter of a small drop of known volume. This technique provides fundamental information about the relationship between contamination, surface energy and performance for adhesively bonded composites. Phase II will use this technique to evaluate a wide range of substrates, adhesives, and contaminants. A practical prototype measuring tool for evaluating surface energy using this technique will be constructed and evaluated in a manufacturing environment.
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 94.06K | Year: 2005
DESCRIPTION (provided by applicant): The goals of this SBIR project are to develop an antimicrobial nano-coating (AMNC) in order to address these important problems: 1) prevention of nosocomial infections by treating hand contact surfaces (e.g. door knobs, railings and bathroom fixtures) and improving the microbicidal and biofilm preventative properties of materials used in medical care (e.g. indwelling catheters, central lines, prostheses and other invasive devices); and 2) treating dental and surgical instruments to help prevent infections in non-ideal settings (e.g.3rd world or battlefield) where maintenance of sanitary facilities is extremely difficult. The AMNCs will be deposited from the vapor phase using a plasma-enhanced chemical vapor deposition (PECVD) process onto a variety of surfaces. Development of a viable AMNC requires thorough understanding of the following areas: 1) Deposition of nanometer-scale films via PECVD that contain leachable silver ions. These will be synthesized with at least two different matrix polymers (organic and inorganic) and a range of silver content via inclusion of silver-containing precursors in PECVD process. The bioavailability of the active metal ions will be controlled by providing these nanocoatings with a range of hydrophilicity and nanometer scaled porosity. 2) Establishing antimicrobial effectiveness of silver-containing PECVD films as a function of structure and composition; and 3) investigation of the specific mechanisms by which AMNCs inhibit bacterial growth and biofilm development. Film composition, thickness, and morphology are all controllable by suitable choice of specific reactant gases and deposition conditions. A successful Phase I project will result in the demonstration of a nanometer-scale antimicrobial coating that has been tested on a panel of approximately 20 of the top bacterial pathogens.