The application of the molecular probes gas‐chromatographic technique to the study of polypropylene transitions

By means of molecular probes gas‐chromatographic technique we have investigated the first and second order transitions of three stereoisomeric polypropylenes: isotactic, syndiotactic, atactic. The choice of the molecular probe for the detection of the first order transition is not particularly difficult. For the 2nd order transition one must choose a molecular probe which, at the transition temperature range, has a appropriate solvent action on the polymer, used as stationary phase: thus, at low temperatures and for hydrocarbon polymers, a suitable molecular probe is a solvent for the polymer and, at high temperatures, a molecular probe is one with limited solvent action and with no specific interactions with the polymer.