Growth Rates and Morphologies of Miscible PCL/PVC Blend Thin and Thick Films

Growth rates and morphologies of thin (0.1−2 μm) and thick (30 μm) films of miscible poly(ε-caprolactone)/poly(vinyl chloride) (PCL/PVC) blends have been investigated. Under isothermal crystallization, PCL growth rates decrease in blend films thinner than 1 μm. However, in pure PCL films, no growth rate dependence is seen at the same thicknesses. In thick films of blends isothermally crystallized at a slow growth rate, two types of spherulites are observed with different growth rates and morphologies. One type of spherulites develops at the free surface of the film whereas the other is located in the bulk. The surface enrichment of the blend in PCL appears to be a key factor explaining the crystallization and morphological behavior of this system.