Crystallite dimensions - characterization of ethene-α-olefin Copolymers with various comonomers and comonomer C contents measured by small- and wide angle X-ray scattering

Ethene-/α-olefin copolymers having a wide range of comonomer contents and comonomers between 4 and 26 carbon atoms in length were characterized by wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS). The data was evaluated with respect to the crystallite size. The half-width of the main crystallite peaks was transformed into the crystallite size s₁₁₀ and s₂₀₀ using the Scherrer equation. It was found to decrease with increasing comonomer content. The crystal lamella thickness was determined from the long period and the crystallinity of the samples. The crystal lamella thickness was found to decrease with decreasing crystallinity following a 3 ^rd order polynomial. This means that the introduction of SCBs leads to a decrease of the crystallite size. A higher M_w leads to an increase of the lamella size in comparison to lower molecular samples with the same crystallinity. The lamella thickness is limited by the average distance between two short-chain branches which is dependent on the comonomer content.