In situ ATR-FTIR Spectroscopy of Poly(ethylene terephthalate) Subjected to High-Temperature Methanol

Summary: In situ ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopy combined with a high-pressure cell has been applied to measure IR spectra of polymers subjected to superheated or near-critical methanol (100– 200 °C). Spectra of poly(ethylene terephthalate) (PET) have been measured under exposure to high temperature methanol using this ATR-FTIR approach to understand at a molecular level the recycling process of PET. The evolution of the structure and the morphology of the polymer has been studied during the methanolysis. The quantity of trans PET conformer is generally used as a tracer of the crystallinity of PET. During depolymerisation of PET the evolution of crystallinity and of trans conformer appears to be different. The dependence of the rate constant on reaction temperature was correlated by Arrhenius plot, which shows activation energy of 5.8 kJ/mol.     

Conformational changes in poly(vinyl alcohol)-graft-polyacrylamide in aqueous solutions vs graft content

Conformational changes have been studied in intramolecular polymer-polymer complexes (intraPC) of graft copolymers of poly(acrylamide) and poly(vinyl alcohol) (PVA-g-PAA) with various numbers of grafts (4-42) per molecule as a function of temperature and copolymer concentration. It is shown that the magnitude of conformational change depends on the grafts content while the temperature range over which the conformation changes occur is essentially determined by copolymer concentration. The conformational changes are reversible on heating and cooling.