Turbidity crystalline polymer blends

Due to light scattering, crystalline polymers mostly yield turbid films.Their blends with other polymers are always demixed because polymers are not able to form mixed crystals. Consequently, crystallizable polymers only yield homogeneous blends above their melting point. As soon as crystallization sets in, the components will separate. 

The depression of the melting point of a crystalline polymer in blends can be used to measure the Flory-Huggins interaction parameter of the mixture. The melting points on heating, or crystallisation points on cooling, can be measured using techniques such as differential scanning calorimetry or by turbidity measurements. 

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