AbstractThe ability of PVC to tolerate large amounts of plasticizers, fillers, and other additives is unique among thermoplastics and has made it possible to develop a wide range of properties in flexible PVC. This versatility, coupled with attractive economics, has been responsible for the growth of flexible PVC over the years. Unfortunately, growth has been slow for many years and flexible PVC markets have been encroached on by competitive materials with higher performance and/or styling advantages. Reasons for the vulnerability of flexible PVC are discussed. In some cases, only minor changes are needed to improve performance while in other cases new developments are needed, many of which are available but not exploited.