Glass transitions and interactions in polymer blends containing poly(4-hydroxystyrene) brominated

The miscibility and interactions of binary blends of poly(4-hydroxystyrene) brominated (P4HSBR) with poly(epsilon -caprolactone) (PCL), poly(vinyl ace tate) (PVA) and poly(vinyl methylether) (PVME) are investigated by means of differential scanning calorimetry (DSC). Glass transition temperatures, T( g)s, are used to assess the miscibility of these systems. All of them were found to be miscible over the whole composition range. T(g)s of the blends are lower than Fox predictions, in contrast to the results previously obtai ned for systems involving poly(4-hydroxystyrene) (P4HS). The melting of PCL in the blends was studied. From the melting temperature depression of PCL in the blends the polymer-polymer interaction parameter was obtained and co mpared with the ones obtained for P4HS/PCL and poly(4-hydroxystyrene-co-met hoxystyrene) (P4HSM)/PCL systems. The best interactions are achieved in P4H S/PCL and the bromination or methoxylation of the P4HS worsen the interacti ons with the PCL. The presence of a cusp in the T-g-composition curve was a nalysed in terms of the Kovacs' theory in systems with P4HS and P4HSBR. (C) 2001 Elsevier Science Ltd. All rights reserved.