The significance of sample preparation of historical and contemporary poly(vinyl chloride) objects to investigate the distribution and changes of molar mass by SEC-MALS-dRI

The distribution of molar mass of historical and contemporary poly(vinyl chloride) objects was determined using size exclusion chromatography with multi-angle light scattering detection. The weight average molar mass was determined for a collection of 57 samples, ranging from 75 to 186 kg/mol with a median of 102 kg/mol. Rigid PVC objects were found to have a significantly lower weight average molar mass (M w = 81 kg/mol) than plasticized ones (M w = 102 kg/mol). Thin objects also exhibited significantly lower M w than bulky objects. A substantial presence of aggregates was noted and characterized as an ‘aggregate ratio’ for the entire collection. Heating a solution of poly(vinyl chloride) in THF at 55 °C for 5 h proved successful in the dissociation of the aggregates and allowed for an accurate determination of molar mass. The uncertainty of the M w determination was statistically evaluated and used to study the effects of accelerated degradation on M w . No statistically significant changes in M w were observed in samples artificially aged at 50 °C to 80 °C for up to 15 weeks, indicating that M w does not decrease during degradation of a PVC heritage object and that accelerated degradation does not lead to polymer crosslinking.