Etude par 1H NMR des groupements chlorométhyles du poly(chlorure de vinyle), 2. Etude par écho de spin et comparaison avec des modèles moléculaires

In order to assign all ? CH₂Cl resonances observed by ¹H NMR in poly(vinyl chloride), (PVC), a preliminary study of the diastereoisomers of molecular models for the groups CH₂Cl? CHCl? [II] and is used, in conjunction with spin echo experiments. The complex region [3,5–4,0 ppm] which corresponds to saturated ? CH₂Cl chloromethyl protons is completely assigned. A separate evaluation of ? CHCl? CH₂Cl [II], ? CH₂? CH₂Cl [III] and is proposed and tested on raw PVC samples. The main interest of this ¹H NMR determination is the fact that raw PVC can be used and that it gives the ratio [II]/[III] which is not accessible by ¹³C NMR on reduced samples.