Non-isothermal crystallization of polyethylenes as function of cooling rate and concentration of short chain branches

Non-isothermal crystallization and melting of metallocene-catalyzed polyethylene was analyzed using the power-compensating calorimetry as function of both cooling rate and branch-degree ranging from 1 to 300 K min−1, and from 0 to 72 hexyl-branches per 1000 carbon atoms, respectively. The onset crystallization temperature decreases linearly with increasing logarithm of cooling rate. The slope of this dependence increases with increasing branch-degree, which is explained by a stronger inhibition of the crystallization by the branches and the decreasing diffusion rate of molecules. The melting endotherms reveal a clear reduction of the crystallinity in the entire temperature range with increasing cooling rate.