Miscibility and phase behavior of poly(D,L-lactide)/poly(p-vinylphenol) blends

The miscibility of poly(D ,L -lactide) (PDLLA) and poly(p-vinylphenol) (PVPh) blends has been studied by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). Phase separation was observed in blends over a wide composition range. A PDLLA-rich phase was found to coexist with an almost pure PVPh phase. The quenched blend samples showed two glass transitions (T_gs), except for a blend with a low PVPh content. However, the T_g value of the PDLLA-rich phase showed a gradual increase with increasing PVPh content. No evidence of interassociation (hydrogen bond formation) between PDLLA and PVPh was found by FTIR. The phase behavior of the blends was simulated using an association model. The results suggested that the equilibrium constant of interassociation between PDLLA and PVPh was small. The phase compositions of the two separated phases were calculated using Fox, Gordon-Taylor, and Couchman equations. The amount of PVPh in the PDLLA-rich phase increased with increasing PVPh content in the blend. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 811–816, 1998