Blends of poly(hydroxyether of bisphenol A) (Phenoxy) and poly(ε-caprolactone) (PCL): Effect of acetylation degree of hydroxyls in phenoxy on miscibility

Abstract

The miscibility between partially acetylated poly(hydroxyether of bisphenol A) (APh) with the crystalline polymer, poly(ε-caprolactone) (PCL) was investigated based on glass transition temperature criteria over the entire range of blend composition. PCL was found to be miscible with APh copolymer in the range of the degree of acetylation obtained. By fitting T g -composition behaviour of all these miscible blends by using the Kwei equation it was shown that q values, which characterize the strength of specific interations, were obtained ranging from −107 for Phenoxy/PCL blends to −132 for 90% (mole fraction) acetylated Phenoxy/PCL blends. The results indicated that the intermolecular hydrogen-bonding interactions between acetylated Phenoxy and PCL were increasingly reduced due to the elimination of the intermolecular interaction sites, as shown by FTIR spectra of the partially acetylated Phenoxy. The segmental interaction energy density B ij was estimated by melting-point depression methods and a binary interaction model. These values suggested that the miscibility in the binary blends of PCL with partially acetylated Phenoxy were primarily responsible for the specific intermolecular interaction and the miscibility of PCL/completely acetylated Phenoxy. FTIR investigations showed that the hydrogen-bonded hydroxyl stretching bands in the partially acetylated Phenoxy shift to higher frequencies with increasing degree of acetylation, which could be due to a balance between the number of strong OH … OH bonds broken and the number of weaker OH … OC bonds formed.