A molecular dynamics (MD) study was performed to analyze the enthalpy of mixing between poly(vinyl chloride) (PVC) and various aliphatic polyesters. The enthalpy of mixing was calculated from the computed cohesive energy densities of: (1) pure PVC; (2) aliphatic polyesters with a molar ratio of CH2/COO groups from 2 to 14; and (3) mixtures of these components. In order to validate the calculation method, mixtures of homologue model compounds with low molar-masses were also examined. An immiscible n-octane/methyl acetate pair having a 50/50 volume ratio showed an enthalpy of mixing of 1 3.43 cal/cm 3 at 298 K, whereas the miscible 2,3-dichlorobutane/diethyl acetate pair of a 50/50 volume ratio showed the enthalpy of mixing of 2 3.20 cal/cm 3 at 298 K. The calculated results for model compound mixtures also showed good agreement with empirical observations from the literature. The cohesive energy density of pure aliphatic polyesters, as the CH2/COO value of polymer chains is increased, decreases gradually owing to the reduced polarity of aliphatic polyesters. The binary interaction parameter (B) of PVC and aliphatic polyester mixtures predicts a maximum miscibility around a CH2/COO ratio of 6, where the calculated B was equal to 2 3.85 cal/cm 3. These results are in semi-quantitative agreement with experimental values from the literature.
Посилання на статтю:
Molecular dynamics simulations of the enthalpy of mixing of poly(vinyl chloride) and aliphatic polyester blends / Sukmin Lee, Jung Goo Lee, Hosull Lee, Stephen J. Mumby // Polymer. – 1999. – N 40. – P. 5137–5145.