Plasticizers are an important component of many adhesives and sealants. A plasticizer is an additive used to increase flexibility or workability of a polymer system. Plasticizers typically affect the viscosity, lower the glass transition temperature, and lower the elastic modulus of a product. Phthalates and terephthalates are an example of effective plasticizer chemistries used in caulks and sealants. This group includes plasticizers such as Butyl Benzyl Phthalate (BBP), DIHP, Diisononyl Phthalate (DINP), Dioctyl Terephthalate (DOTP), and DBT. Dibenzoate plasticizers such as Dipropylene Gycol Dibenzoate are also commonly used. Plasticizers are typically chosen based on polymer compatibility and the desired properties of the end product. By choosing a plasticizer that is compatible with the polymer, it protects the plasticizer for leaching out of the product and thus losing the benefits of plasticization. Plasticizer permanence, or resistance to migration out of the adhesive or sealant, plays a role in the longevity of a product. Permanence can be affected by weathering such exposure to sunlight and extreme temperatures, or extraction by substances such as soapy water. Loss of plasticizer results in stiffening, shrinkage or the caulk or sealant becoming brittle. Generally speaking, sealants composed of acrylics, polyvinyl acetate (PVA), and polyvinyl chloride (PVC) would do will with phthalates, terephthalates, benzoates, and epoxidized oils such as Epoxidized Soybean Oil (ESO). Polyamides and polysulfides may do well with a phosphate ester such as Tributyl Phosphate (TBP) or Trioctyl Phosphate (TOF), whereas, Polyurethanes and epoxies might be better off with use of polymeric polyesters. The amount of plasticizer needed varies by formulation, but can be anywhere between 5 – 50% of the product by weight.