Résumé
From the literature, it is well known that poly(caprolactone)/poly(vinyl chloride) (PCL/PVC) and poly(caprolactone)/chlorinated poly(vinyl chloride) (PCL/CPVC) blends are miscible, at any composition. However, PVC and CPVC are immiscible. It is shown, in this study, that the addition of PCL to a PVC/CPVC mixture allows the observation of a single glass transition temperature (
T
g) at PCL contents larger than 40% at high PVC/CPVC ratios and at PCL contents larger than about 26% at low PVC/CPVC ratios. The observation of a single
T
g does not necessarily mean that the three polymers form a homogeneous phase, since it can also correspond to the coexistence of two homogeneous binary PCL/PVC and PCL/CPVC phases having close values of
T
g. The
one-T
g
two-T
g
boundary of this ternary mixture was established; it is observed that it is not symmetrical with respect to the PVC and CPVC apexes. This behaviour can be modelled with thermodynamic interaction parameters of −0.3 between PCL and PVC, −1.8 between PCL and CPVC, and +3.5 between PVC and CPVC. Finally, a variety of phase behaviour was observed in the ternary diagram region where several
T
g values are recorded.