The Elastic Range of Polymers and Its Change by Plasticization

Thermal diffusivity and conductivity measurements of polymers show two transitions, the main glass transition and a now, sidegroup transition. Sidegroups with a very low transition temperature cause plasticization of the polymer. Thermal measurements prove that good plasticizers have a structure similar to polymers; they possess bulky anchor groups and rotatable side chains which by their free rotation in the liquid state create a great number of isomers. These are a great barrier to nucleatlon, permitting an easy glass formation. The elastic range of polymers is the temperature interval between the glass transitioned the flow-temperature. Good solvents in contrast to bad ones diminish the extension of this range even if added only in small amounts. Dissolution measurements are a powerful tool for judging plasticizers.