ABSTRACT
The parameters of molecular-weight heterogeneity are measured directly by physical methods, but no such methods exist for measuring the FTD parameters, and so one has to combine physical and physico-chemical methods. Ebulliometry, cryoscopy, vapour pressure osmometry based on measuring the thermal effects of condensation, and gel permeation chromatography can be used to measure the number-average molecular weight of oligomers. The process of the establishment of a stationary state is quite long, due to the dynamic diffusion equilibrium caused by the rate of condensation from the vapour phase and the kinetics of the gradient equalization in the drop. The measurement time can be reduced by decreasing the drop volume, which leads to a sharp change in the shape of heating vs. time curves. The concentrations of functional groups in oligomers are determined with the help of a variety of chemical and physical techniques.
