Study of hydrogen-bonding strength in poly(epsilon-caprolactone) blends byDSC and FTIR

The hydrogen-bonding strength of poly(epsilon -caprolactone) (PCL) blends w ith three different well-known hydrogen-bonding donor polymers [i.e., pheno lic, poly(vinyl-phenol) (PVPh), and phenoxy] was investigated with differen tial scanning calorimetry and Fourier transform infrared spectroscopy. All blends exhibited a single glass-transition temperature with differential sc anning calorimetry, which is characteristic of a miscible system. The stren gth of interassociation depended on the hydrogen-bonding donor group in the order phenolic/PCL > PVPh/PCL > phenoxy/PCL, which corresponds to the q va lue of the Kwei equation. Tn addition, the interaction energy density param eter calculated from the melting depression of PCL with the Nishi-Wang equa tion resulted in a similar trend in terms of the hydrogen-bonding strength. Quantitative analyses on the fraction of hydrogen-bonded carbonyl groups i n tile molten state were made with Fourier transform infrared spectroscopy for all systems, and good correlations between thermal behaviors and infrar ed results were observed. (C) 2001 John Wiley & Sons, Inc.