chemically converting post-consumer PET into its oligomers with-out employing a huge amount of glycol and resulting in final prod-ucts less containing free reagents.
To definitely assess if these products can be used as a secondary
plasticizer for flexible PVC compounds, their thermal properties
were also evaluated by DSC (Fig. 3). Either the Tm as Tc decreased
as the amount of DEG increased (see alsoTable S2 in Appendix A )
for post-consumer and virgin PET. However, the crystallinity of the
degraded samples (SPs) was slightly higher than that of the start-ing polyester owing to easier packing of shorter polymer chains.
The starting post-consumer PET has a broad melting range with
two well-defined crystalline domains; by increasing the polyester
degradation, a broadening of the melting curve is observed in
agreement with the formation of chains with different lengths
(Fig. 3).
In particular, the SP3 sample was characterized by a Tm of
192 C that is within the processing temperature range of PVC resin
(180–200 C) fundamental for its exploitation as plasticizer in PVC
formulations. Then, among the solid products, the oligoester SP3
was used as solid secondary plasticizer (SP) for the preparation
of flexible PVC compounds.