Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 34: Crystallization, Nucleation, Self Assembly I (joint session CPP/DY, organized by CPP)

CPP 34.2: Vortrag

Mittwoch, 9. März 2016, 10:00–10:15, H42

Elementary steps of chain folding in a melt of linear polyethylene * a proposal for discussion. — •Heinz H. W. Preuß — Sedanstr. 6, 31785 Hameln

As far as lamellae of crystalline polyethylene from solution or melt consist of close folded molecular chains (Preuss DPG Spring Meeting 2015, CPP 6.7), one has to find out how the folding can occur. The answer is in the understanding of the limited mobility and flexibility of polymer molecules in a melt. If the molecules are with a large portion nearly close and parallel packed, they can move freely in the direction of their backbone by *worming*(Faraday Discussion 1979, F. C. Frank, p 7 ff., A. Keller, p.146 ff.).In the direction perpendicular to the backbone, molecules have 8,5 % (1/12)of their diameter as average room of move for isomeric exchange of the place of C and H atomes. By simultaneous exchange of some C-H-pairs one can get pairs of folds in an extended chain keeping its general orientation. This would be possible with small molecules neighbouring only and should occur already during polymerization in solution or gas. The expression *adjacent reentry* is in this context a source of missunderstandig, for it provokes the meaning, molecules would move out of the place of junktion in a lamella and would reenter nearby after returning, a probably impossible motion.