Tacticity Effect on Miscibility

Generally, the temperature dependence of the segmental interaction parameter can be expressed as x = BIT. The temperature dependence of X was obtained as 

Equation 17.6 is found to indicate an UCST behavior, that is, the mixture undergoes phase separation when dropping the temperature below the spi-nodal point. The interaction parameter x at the spinodal point Xs is given by 

The spinodal temperature of the DSPSl/HAPSl (50/50) mixture can be calculated as 286K using Equations 17.6 and 17.7. 

It should be noted that the segmental interaction parameter obtained from d-SPS/h-APS mixtures includes not only the tacticity effect but also the isotopic effect, that is, the interaction between deuterated and hydrogenous polymers [10]. Therefore, a comparison of the results with the literature on 

Comparing Equation 17.6 with Equations 17.8 and 17.9, the DSPSl/HAPSl (50/50) mixture indicates a stronger temperature dependence of the % parameter, and it is about 10 times larger than those of the d-APS/h-APS mixtures. Hence, at a given %, the spinodal temperature of the d-SPS/h-APS mixture is higher than that of the d-APS/h-APS mixture. 

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