Assessing the Variable Molecular Architecture of Poly(ethylene terephthalate) Under Reactive Modification by Melt and Dilute Solution Rheology

Two simple methods are described that utilize melt or dilute solution rheology in characterizing transfomations in molecular architecture induced on an originally linear PET during the early stages of reactive extrusion. A plausible senario for the shape variation and relative difficulty of the new polymers formed is assumed, from which expressions for the evolving melt and intrinsic viscosity of the reacting PET are derived. The model is tested using two separate sets of viscometric data refering to PET modified at various degrees. Quantitative agreement is found between the two methods in estimating the composition of the various types of PET species present.