AbstractDiffusional exchanges in plasticized PVC applications comprise a critical aspect of much of the published work, which has been intended to study plasticizer migration into simpler extractants, enabling the various parameters involved in migration to be studied in isolation. In this study the migration of dioctyl phthalate into petroleum oils is investigated with emphasis on prior sample history. Simultaneously, the penetration of the liquid environment into the sheets is monitored. Plasticized PVC samples were prepared containing different amounts of plasticizer. The samples are immersed in paraffin oil until the plasticizer concentration reaches a predetermined value. Afterwards the samples are immersed in white spirit and their migration behavior is compared with that of new samples containing this predetermined plasticizer content, i.e., excluding the prior desorption cycle. Under these experimental conditions the parameters studied include immersion time, immersion temperature, initial plasticizer content and specimen thickness. The results obtained, suggesting considerable restriction of the migration activity for the two‐stages specimens, are discussed in terms of surface‐depleted concentration profiles and structure rearrangement mechani
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