Unlike inorganic and organic molecules, in semicrystalline polymers melting gets complicated because of the requirement of conformational transformation of the chain segments, where part of the same chain resides in the crystal and also in the amorphous phase. The chain segment residing in the amorphous part can be constrained, either due to adjacent or nonadjacent re-entry leading to a different nature of chain folding, and arising differences are observed in local chain mobility due to differences in topological constraints. Thus, different conformational possibilities in the amorphous region of the semicrystalline polymer has implications on melting temperature and the processes involved in the order to the disorder phase transformation. With a series of experiments on ultra high molecular weight polyethylene, where the topological constraints are tailored by adopting a different synthesis route, it is shown that melting behavior cannot be fully explained by Gibbs-Thomson equation only. Nonlinearity in melting temperature on heating rate invokes kinetics in the melting process, where depending on the heating rate melting can occur either via successive detachment of chains and their diffusion in the melt or by cluster melting. The role of superheating on melting process is also addressed. © 2011 American Chemical Society.