Dental Materials Properties Lecture 2

Study Notes

Wettability indicates a liquid's affinity for a solid, measured through the contact angle of a liquid drop.
Contact angle of 180° signifies no wetting, while 0° indicates complete wetting.
Surface energy is the excess energy at a material's surface compared to its bulk, influenced by attraction forces among surface molecules.

Adhesion describes the attraction between two contacting surfaces, crucial for material bonding.
Micromechanical bonding relies on interfacial forces, enhanced when an adhesive penetrates a rough surface.
Bonding can occur via chemical forces, mechanical interlocking, or a combination of both.

Surface tension is the tendency of fluid surfaces to minimize area, resulting from molecular attraction imbalances at the surface.
Cohesion refers to the attraction between molecules of the same species, influencing liquid properties.

Stress is defined as force per unit area within a material under external load.
Strain quantifies deformation as the change in length divided by the original length.
Shear stress measures time-dependent plastic strain in a solid under consistent load.

Viscosity is the measurement of a fluid's resistance to flow; it describes how substances deform and flow.
Rheology studies the flow characteristics indicating how materials behave under various forces.
Newtonian fluids have a consistent viscosity, while non-Newtonian fluids exhibit varied flow properties:
- Dilatant: Flow decreases with increased strain until reaching a constant.
- Pseudoplastic: Flow increases with increased strain.
- Plastic: Resembles rigid material until a minimum strain is applied.