K. K. Chee

Molecular weight dependence of surface tension of polystyrene as studied by the corresponding states principle

The corresponding states correlation with the surface tension (γ) of polymers after Patterson et al. has been modified by considering the molecular weight (M) dependence of the equation-of-state parameters, which may be estimated by either the Flory-Orwoll-Vrij (FOV) theory or the cell model (CEM). It has been found that the corresponding states principle-cum-FOV predicts the γs of polystyrene melts over a wide range of M satisfactorily. However, its CEM counterpart is rather irrelevant to the present system of interest. Indeed, the three classical linear equations proposed for the variations of γ with M are intimately correlated with the foregoing models, and hence, facilitating the predictions of the γs of polymer end groups.

Binary interactions in dimethyl terephthalate/bis(2‐ethylhexyl)adipate/poly(vinyl chloride) blends studied by melting point depression method

A novel approach is developed to estimate the interaction energy density, B, of polymer solutions by the melting point depression method using a crystallizable molecule as the probe. It rests on the classical Flory-Huggins lattice model of polymer solutions, and considers the polymer-solvent interaction parameter to be concentration dependent. The ternary system dimethyl terephthalate (DMT)/bis(2-ethylhexyl)adipate (DOA)/poly(vinyl chloride) (PVC) is chosen for the present study. The data of B for the three possible binary interactions are reported as the functions of composition at elevated temperatures. For a plasticized PVC resin containing 20 vol % DOA, the B is estimated to be 6 MJ m -3 , which is approximately 2 MJ m -3 higher than the B value cited in the literature for the PVC mixed with almost 100% DOA. The thermodynamic stability of the ternary system is discussed.