BOND QUALITY EVALUATION USING ADHESIVE DOPED WITH MAGNETO-ELECTRIC NANOPARTICLES

Adhesive bonding for composite structures offers multiple advantages over mechanical fasteners. Although the use of adhesive bonding has increased in the aerospace industry, it has still not replaced mechanical fasteners due to it being harder to inspect for damage after being manufactured/assembled, causing unreliability. Therefore, intensive quality control is needed while manufacturing to avoid weak bonds or any type of imperfection at the adhesive-adherend interface. To ensure the reliability of an adhesive bond, this project focuses on the advancement of a non-invasive field tool for adhesive quality evaluation. The tool developed is based on a B-H looper system, which can approximate the quality of an epoxy-based adhesive containing magneto-electric nanoparticles (MENs) by detecting changes in electric fields at the molecular level. Epoxy based adhesive samples containing 5 vol. % of MENs were manufactured and then scanned using the B-H looper system to correlate their magnetic signature as a function of curing time. It was determined that the magnetic signal converged between curing hours 10 and 12, indicating proper curing. Plain adhesive dogbone samples were used to determine the maximum tensile stress of the adhesive as a function of curing time, which also started converging at around the same curing hours until reaching ~41 MPa. Additionally, the evolution of the glass transition temperature of the adhesive was evaluated during the first curing hours. Convergence began at a curing time of 10 hours until reaching ~137 ⁰ C for fully cured samples. B-H looper magnetic signatures, tensile stresses testing, and glass transition temperatures were all correlated indicating a fully cured adhesive sample between 10 and 12 curing hours. These studies demonstrate the capabilities of the B-H looper system as a non-invasive inspection tool for adhesive quality.

Making an open-tray implant or abutment-level impression technique easier

Various methods exist for taking implant impressions. The open-tray or pick-up impression technique is one of the conventional methods for transferring the impression coping from the implant to the impression. In this method, a window directly above the implant is made in a stock or custom tray to allow access to the impression coping. Traditionally, the window is either left open, or closed with melted wax or foil. This technique tip describes a modification to create a stable and secure seal over the opening using rayon-based adhesive tapes. The benefits of this modification over the conventional open-tray technique are due to the enhanced adhesive quality of the materials to metal or plastic. Because there is less chance of impression material leaking from the tray window into the mouth, it is more comfortable for patients and less messy for clinicians. The benefit of this method over the closed-tray technique is the ability to feel for the head of the impression coping at the same time as making sure the impression material is in good contact with the underlying structures. It is easy to use, and efficient in terms of time and cost.