Melting kinetics in polymers.
In polymers, it is possible to obtain single chain forming single crystals. It is feasible to melt these crystals by simple consecutive detachment of chain segments from the crystalline substrate and its diffusion into the melt. However, complication in the melting process occurs when the chain in the process of detachment from the surface is shared between different crystals. Experimentally, a clear distinction in different melting processes is observed, by the differences in the activation energies required for the consecutive detachment of chain segments or of segments having topological constraints. The consecutive detachment of free chain segments starts at the melting temperature predicted from the Gibbs-Thomson equation, whereas higher temperature or time is required if the chain has to overcome the constraints.
Lippits
D R
DR
The Dutch Polymer Institute/Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Rastogi
S
S
Höhne
G W H
GW
D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D044367:Phase Transition; D011095:Polyethylenes / Q000032:analysis* / Q000737:chemistry*; D011108:Polymers / Q000032:analysis / Q000737:chemistry*; D044366:Transition Temperature
D011095:Polyethylenes; D011108:Polymers; C111601:ultra-high molecular weight polyethylene