Thermodynamics of poly(1-butene)/diluent systems

The low-molecular-weight semicrystalline isotactic poly(1-butenes) were synthesized using metallocene catalyst. Molecular weight was determined using GPC. Chemical structure was verified using differential scanning calorimetry. Recent work presents SLE phase diagrams for two samples of iPBu-1 (M-n = 16 812 Da and M-n = 18 708 Da) in many organic solvents (n-octadecane, 3-methylpentane, 2,2-dimethylbutane, cyclodecane, toluene and ethylbenzene) being the model representatives of gasoline and motor oils. Solubilities were studied using dynamic method. Performing these experiments over a large concentration range allowed the construction of the T-x phase diagram of the polymer/diluent systems. It was found that the solubility of iPBu-1 decreases with an increase of the hydrocarbon's carbon atoms number. The lower-molecular-weight iPBu-1 shows better solubility than the higher-molecular-weight iPBu-1. Moreover, the excess Gibbs energy models were used to describe the nonideal behaviour of the liquid phase and to estimate the solubility of iPBu-1 in the whole range of mole fraction. Activity coefficients at infinite dilution for polymer and solvent were determined from the solubility measurements and were predicted by the UNIFAC-FV model and molecular Monte Carlo simulation. (c) 2005 Elsevier B.V. All rights reserved.