Additives that increase the plasticity of a material (the ability of a substance to take the desired shape) or decrease its viscosity are called plasticizers. These substances may be intended to change the physical properties .

They reduce the bond strengths between polymer molecular chains to make the material more flexible . Under normal conditions, PVC is a hard material because its intermolecular distance is short and its intermolecular forces are very strong. If they are heated, the intermolecular energy becomes greater than the intermolecular force, which widens the molecular distances and causes the resin to soften. Plasticizers are added to the PVC at this stage . Plasticizers move between PVC molecules and prevent the distance between polymer molecules from decreasing. Thus , the polymer molecules can be kept the same even under normal conditions and the softness of the material is preserved . These processes take place because of the role plasticizers play and, technically speaking, this process is called plasticization. While PVC molecules have positive and negative polarity, plasticizers have polar and nonpolar parts. PVC molecules and plasticizers are electrically attracted to each other and the nonpolar cut opens the distance between polymer molecules to maintain softness. PVCs softened by plasticizers are called flexible PVC materials. Plasticizers are not just additives. In addition, they are the main components that maintain the plasticization efficiency and adapt well to PVC, as well as show the physical properties of polymers and have low volatility.

The plasticizer must first be compatible with the resin, the more compatible the two, the better the plasticizer effect. The addition of a plasticizer makes hard and rigid plastics soft and elastic, reducing the plastic-glass transition temperature. Generally speaking, plasticizers are expected to be of high purity, colorless, neutral to reactions, odorless, tasteless and always of the same quality.