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A binder or binding agent is any material or substance that holds or draws other materials together to form a cohesive whole mechanically, chemically, by adhesion or cohesion. More narrowly, binders are liquid or dough-like substances that harden by a chemical or physical process and bind fibres, filler powder and other particles added into it.
As this example shows, there can be no sharp boundary between molecular and network covalent solids. Intermediate kinds of bonding: A solid with extensive hydrogen bonding will be considered a molecular solid, yet strong hydrogen bonds can have a significant degree of covalent character. As noted above, covalent and ionic bonds form a continuum ...
The strength of the adhesion between two materials depends on which of the above mechanisms occur between the two materials, and the surface area over which the two materials contact. Materials that wet against each other tend to have a larger contact area than those that do not. Wetting depends on the surface energy of the materials.
Mucoadhesion involves several types of bonding mechanisms, and it is the interaction between each process that allows for the adhesive process. The major categories are wetting theory, adsorption theory, diffusion theory, electrostatic theory, and fracture theory. [5]
The adhesive forces are usually based on physical interactions, for example, such as those between polar or polarisable groups, on hydrogen bonds, or van der Waals forces. When bonding plastics, in particular with solvent-based adhesives, diffusion processes can also play a role. In this case, the plastic at the substrate surface is dissolved ...
Pre-tensioned concrete is a variant of prestressed concrete where the tendons are tensioned prior to the concrete being cast. [1]: 25 The concrete bonds to the tendons as it cures, following which the end-anchoring of the tendons is released, and the tendon tension forces are transferred to the concrete as compression by static friction.
Unlike regular concrete, ECC has a tensile strain capacity in the range of 3–7%, [1] compared to 0.01% for ordinary portland cement (OPC) paste, mortar or concrete. ECC therefore acts more like a ductile metal material rather than a brittle glass material (as does OPC concrete), leading to a wide variety of applications.
An example of a dative covalent bond is provided by the interaction between a molecule of ammonia, a Lewis base with a lone pair of electrons on the nitrogen atom, and boron trifluoride, a Lewis acid by virtue of the boron atom having an incomplete octet of electrons. In forming the adduct, the boron atom attains an octet configuration.