High-Field1H-NMR Study of Poly(Vinyl Chloride) Defects

Abstract

Abstract Radical poly(vinyl chlorides), (PVC), obtained in bulk and in suspension polymerizations, and their low molecular weight extracts have been thoroughly studied by high-field NMR to obtain better qualitative and quantitative analyses of their structural defects. Assignments have been achieved by 1H-1H decoupling experiments and hyperfine spectral structure analysis of model compounds and low molecular weight extracts. Strong effects of the nature of the solvents used in 1H-NMR analysis were observed. Most of the defects of these radical PVC's have been quantitatively estimated in terms of average number values in correlation with their [Mbar]n. End-groups of type [I'] (= −CH2−CH[dbnd]CH[sbnd]CH2C1) are about 0.5 per chain; internal double bonds can only be estimated by difference, and their amount increases with increasing conversion. A very low quantity of vinyl chain end [I'] ([dbnd] [sbnd]CHC1[sbnd]CH[dbnd]CH2) has been found only in low molecular weight extracts. For the three probable saturated chloromethyl ends [II] ([dbnd][sbnd]CHCl[sbnd]CH2Cl), [III] ([dbnd] [sbnd]CH2[sbnd]CH2Cl), and [IV] ([dbnd] >CH[sbnd]CH2C1), only [II] and [III] were definitely identified. Finally, in taking into account all the endgroups, it has been concluded that branches would be grafted throughout the process. On the average, 4 to 5 branches have been found per chain of high molecular weight PVC.