Evaluation of Varnishes to Slow Down the Aging of Plasticized PVC

Vollständiger Abstract

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ABSTRACT This study investigates the preventive and curative potential of surface varnishes to mitigate the aging of plasticized PVC (p‐PVC), with particular emphasis on the influence of the PVC formulation on coating efficiency. Two industrial p‐PVC formulations were studied: PVC‐nP plasticized with Diisodecyl Phthalate and Epoxidized Soybean Oil, and PVC‐wP containing an additional phosphate plasticizer, each in pigmented and unpigmented versions. Three aqueous polyurethane‐based varnishes, vPU, vVA, and vFC were applied, and the samples were subjected to artificial aging under cyclic temperature and humidity conditions. Color changes associated with dehydrochlorination and plasticizer migration were monitored. The results demonstrate that the effectiveness of barrier coatings is strongly formulation‐dependent. Phosphate‐containing PVC‐wP exhibited faster mass loss due to the early migration of the phosphate plasticizer, limiting the protective effect of the investigated coatings, whereas the vPU varnish markedly improved the stability of PVC‐nP by reducing both color variation and plasticizer loss. Moreover, coating efficiency depended not only on the PVC formulation but also on the degradation state of the material at the time of application, with earlier application providing greater protection.