Determination Of Binding Strength Research Articles

Novel Facile Technique for the Determination of Binding Strength of Adhesives

Abstract Second to the wide application of different types of adhesives in various industries, offices, and homes and to the paucity of raw materials for the production of adhesives, as well as constraints in access to the conventional instruments for determination of binding strength, especially in underdeveloped and developing countries, there is a need to source and produce adhesives locally from readily available and inexpensive raw materials and to develop simple and reliable techniques to determine the binding strength. In this work, adhesives were produced from pumpkin and watermelon seeds. The binding strength of the adhesives was successfully tested using a simple technique involving a retort stand and standard objects of known mass. The adhesives were of good quality and easily applied, especially on paper, foam, footwear, and wood works. This novel technique provides a very easy and inexpensive route for the determination of binding strength as it does not require electric power, advanced technical skills, or other chemicals.

Determination of binding strength and kinetics of binding initiation

The adhesive properties of the mouse P388D1 macrophage-like line were explored. Cells were deposited in glass capillary tubes, and the kinetics of adhesion and spreading were studied. Binding involved the cell metabolism since it was decreased by cold, azide, or a divalent cation chelator. Glass-adherent cells were subjected to calibrated laminar shear flows with a highly viscous dextran solution. A tangential force of about 5 X 10(-3) dyn/cell was required to achieve substantial detachment. The duration of application of the shearing force strongly influenced cell-substrate separation when this was varied from 1-10 s. Further, this treatment resulted in marked cell deformation, with the appearance of an elongated shape. Hence, cell-substrate separation is a progressive process, and binding strength is expected to be influenced by cell deformability. The minimum time required for adhesion was also investigated by making cells adhere under flow conditions. The maximum flow rate compatible with adhesion was about 1000-fold lower than that required to detach glass-bound cells. A simple model was devised to provide a quantitative interpretation for the experimental results of kinetic studies. It is concluded that cell-to-glass adhesion required a cell-substrate contact longer than a few seconds. This first step of adhesion was rapidly followed by a large (about 1000-fold) increase of adhesion strength. It is therefore emphasized that adhesion is heavily dependent on the duration of cell-to-cell encounter, as well as the force used to remove so-called unbound cells.

Interaction of acridine orange and polyanions: fluorimetric determination of binding strengths and the influence of simple electrolytes

Binding affinities of Acridine Orange and six polyanions have been determined by measuring association constants in essentially salt-free solution, and also by observing competition between the dye and a simple salt for the polyanion site. Differences were found in the dye-binding order for the six polyanions using the two techniques. These differences were related to the breakdown in the uniform binding behaviour of carboxy and sulphate groups bound to the same polymer backbone as the salt concentration is increased. A mechanism is proposed which fits the thermodynamic parameters calculated by the application of Schwarz treatment and the Langmuir isotherm. The difference in the free-energy of binding between the strongest binding polymer, polystyrene sulphonate (ΔG°=–41 kJ mol–1) and the weakest binding, hyaluronic acid (ΔG°=–29 kJ mol–1) could be accounted for by considering coulombic site-dye interactions which destabilise the dye aggregates. The main influence promoting dye binding appears to be the free-energy of dye aggregation.The degree of co-operativity of dye binding, q, has also been determined. An attempt has been made to relate this parameter to the physical properties of the polyanion chain. It appears unlikely that q has the significance initially attached to it.