ABSTRACT
Plasticizers are nonvolatile solvents, the purpose of which is to make the mixture of polymer and plasticizer softer, more flexible, and more easily worked. Normally, the rigid polymer molecules are held together by van der Waals forces, hydrogen bonding, polar forces and, as described earlier, these bonds may be broken and the molecules separated by a solvent: This process may require heat. There may be crystalline regions into which the plasticizer (solvent) penetrates with great difficulty and noncrystalline regions into which it penetrates slowly without heating. Thus, rigid polyvinyl chloride, for example, may be quite insoluble at moderate temperatures in solvents or plasticizers that have the same cohesive energy density (CED) as the polymer; hence, a dispersion of the polymer in the plasticizer may
be made that is essentially a stable nonaqueous dispersion. The dispersion is called a plastisol, and it may have the consistency of slush.
