2.4.6. Migration test
The plasticizer migration was determined by following the
international standard UNI EN ISO 177, 2001 . This method is based
on the tendency showed by the plasticizer to migrate from poly-mer matrix when two materials with different plasticizer concen-trations are put in intimate contact.
The runs were carried out at 70 C under continuous air circula-tion (Binder oven) for 24 h with an arrangement composed by
three layers, each layer consisting on 2 un-plasticized polymer
sheets (rigid PVC) separated by 1 plasticized polymer layer (flexi-ble PVC compound, Plast_x sample) under a 5 kg weight of pres-sure. The specimens were disks with a diameter of 50 mm with a
thickness of 0.55–0.58 mm for flexible PVC compounds and 0.60–
0.68 mm for rigid PVC compound. The migration test of plasticized
samples was carried out three times for each sample and the data
reported as percentage of weight variation (by gravimetric mea-surement), with an error range expressed as variability (standard
deviation). All the samples were conditioned under dried atmo-sphere at room temperature for at least one day before testing.
The disks were prepared by compression moulding at 180 C and
80 Bar of pressure.
The migration behavior of samples containing only DEHP as
plasticizer was evaluated by plotting the migration test results,
obtained experimentally for the reference samples (R1, R2, R3,
Table 2), against their ratio PVC/DEHP and by fitting the data with
the best mathematical correlation by employing Origin 7.0 Soft-ware tool (Fig. S1 in Appendix A ).
2.4.6. Migration testThe plasticizer migration was determined by following theinternational standard UNI EN ISO 177, 2001 . This method is basedon the tendency showed by the plasticizer to migrate from poly-mer matrix when two materials with different plasticizer concen-trations are put in intimate contact.The runs were carried out at 70 C under continuous air circula-tion (Binder oven) for 24 h with an arrangement composed bythree layers, each layer consisting on 2 un-plasticized polymersheets (rigid PVC) separated by 1 plasticized polymer layer (flexi-ble PVC compound, Plast_x sample) under a 5 kg weight of pres-sure. The specimens were disks with a diameter of 50 mm with athickness of 0.55–0.58 mm for flexible PVC compounds and 0.60–0.68 mm for rigid PVC compound. The migration test of plasticizedsamples was carried out three times for each sample and the datareported as percentage of weight variation (by gravimetric mea-surement), with an error range expressed as variability (standarddeviation). All the samples were conditioned under dried atmo-sphere at room temperature for at least one day before testing.The disks were prepared by compression moulding at 180 C and80 Bar of pressure.The migration behavior of samples containing only DEHP asplasticizer was evaluated by plotting the migration test results,obtained experimentally for the reference samples (R1, R2, R3,Table 2), against their ratio PVC/DEHP and by fitting the data withthe best mathematical correlation by employing Origin 7.0 Soft-ware tool (Fig. S1 in Appendix A ).
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