Kinetic of crystallization from the melt and chain folding in polyethylene fractions revisited: theory and experiment

TL;DR: This work addresses several unsolved problems regarding calorimetry of polymers, for example determination of baseline heat capacity, which is related to the problem of crystallinity determination by DSC, or the occurrence of multiple melting peaks.

TL;DR: In this article, a review of the growth, branching and twisting of spherulite is presented, while maintaining an appreciation for the historical context of the field gradient and the crucial role of self-generated fields ahead of the crystal-melt interface.

TL;DR: In this paper, a negative polymer−polymer interaction energy density was calculated on the basis of the melting point depression of PEO and a negative deviation of Tg from the weighted average values observed.

TL;DR: In this article, the melting and crystallization behavior of poly(ethylene glycol) (PEG) with different molecular weights and chosen blends of PEG is investigated by means of differential scanning calorimetry (DSC) operating in dynamic mode at different heating rates.

TL;DR: In this paper, the authors studied possible motions for one polymer molecule P performing wormlike displacements inside a strongly cross-linked polymeric gel G. The topological requirement that P cannot intersect any of the chains of G is taken into account by a rigorous procedure: the only motions allowed for the chain are associated with the displacement of certain "defects" along the chain.

Abstract: We discuss possible motions for one polymer molecule P (of mass M) performing wormlike displacements inside a strongly cross‐linked polymeric gel G. The topological requirement that P cannot intersect any of the chains of G is taken into account by a rigorous procedure: The only motions allowed for the chain are associated with the displacement of certain “defects” along the chain. The main conclusions derived from this model are the following:(a) There are two characteristic times for the chain motion: One of them (Td) is the equilibration time for the defect concentration, and is proportional to M2. The other time (Tr) is the time required for complete renewal of the chain conformation, and is proportional to M3.(b) The over‐all mobility and diffusion coefficients of the chain P are proportional to M−2.(c) At times t < Tr the mean square displacement of one monomer of P increases only like 〈(rt − r0)2〉 = const t1/4.These results may also turn out to be useful for the (more difficult) problem of entangle...

TL;DR: On the basis of the nucleation theory developed by Volmer, Becker, and co-workers, and the theory of absolute reaction rates, an expression for the absolute rate of nucleation in condensed systems was derived in this paper.