The degree of crystallinity exhibiting a spatial distribution in polymer films

The degree of crystallinity in polymer materials significantly affects their physical properties. However, the distribution of the degree of crystallinity within polymer materials has not been considered even though it should, equally importantly, affect the properties. Herein, we investigate how the degree of crystallinity is spatially distributed in poly(ε-caprolactone) (PCL) films utilizing Raman spectrum. The results indicate that the degree of crystallinity is not uniform throughout the films but presents a distribution along the radial direction of spherulite, with lower degree of crystallinity in the spherulite center. Consequently, the melting range exhibits a similar spatial distribution, with the spherulite center starts to melt at a lower temperature. This work begins to provide an additional structural feature of crystalline polymers that should greatly affect the polymer properties.