Determination of the plasticizer content in poly(vinyl acetate) paint medium by pyrolysis–silylation–gas chromatography–mass spectrometry

The use of plasticizers in emulsion paints is intended to provide optimal mechanical properties to polyvinyl acetate polymers (PVA), making them suitable as binding media for paintings. The loss of these properties with ageing is often related to the slow migration and evaporation of such plasticizers, resulting in severe embrittlement and potential damage to the paint film.A new method consisting of the quantification of the plasticizer content of PVAc samples with “on-line” silylation–pyrolysis with hexadimethyldisilazane (HMDS) as a derivatization agent in Py–GC–MS and using 1,4-dibromebenzene as an IS is proposed here. For this purpose, two series of specimens of Mowilith 50® (a pure PVAc resin) with the addition of two different plasticizers, diethylphthalate (DEP) and dibutylphthalate (DBP), were prepared as thin films and submitted to a multi-step UV-light artificial ageing program so that the plasticizer content was determined at each ageing stage.