A Technique for Evaluating Dental Adhesives
A method is proposed for evaluating the strength of an adhesive joint. It is basically a fracture mechanics approach which recognizes that the strength of a joint depends on adhesive thickness, elastic properties of adhesive and teeth, joint geometry, sizes of flaws, and other factors. The "blister" technique is proposed as a useful means of quantitatively determining the quality of an adhesive joint.
On The Strength of Adhesive Bonds Between Rigid, Non-Crystalline Polymers
Abstract The relatively high strengths exhibited by well-prepared, rigid adhesive bonds partly reflect the crack-growth inhibiting properties of the surrounding bulk. Dispersion forces alone are unable to inhibit crack growth significantly, as is indicated, for example, by the low strengths of low molecular weight glassy polymers. The source of crack-growth inhibition of adhesive bonds was revealed by examining crack fronts with a microscope. Examined were crack fronts along the self-bond between pieces of poly(methyl methacrylate) and along the adhesive bond between pieces of poly(methyl methacrylate) and polystyrene. Associated with each crack front were two sets of interference fringes, indicating the presence of a craze preceding the crack. Crazes form in high molecular weight brittle polymers, and their presence along the adhesive bond ahead of the crack indicates the involvement of the high molecular weight bulk polymer adjacent to the bonding plane. Crazes ahead of cracks are known to inhibit fract...
Rotating dialysis cell as in vitro release method for oily parenteral depot solutions.
The purpose of the study was to investigate an in vitro release method based on a rotating dialysis cell for parenteral oil depot formulations using different model conditions and test formulations. The total amount of drug released from the rotating dialysis cell was in accordance with the theoretical values calculated from the partition coefficients. The release rates were shown to depend on the total amount of drug available for the release process and to follow first order kinetics. The rotating dialysis cell has a potential as in vitro release method for characterization of oily depot formulations for parenteral administration.