ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Thermodynamics of eutectoid copolymers is based on the assumption that the co-units are eutectic units. At low concentration of one of these units (non-crystallizable units, nc-units), crystallizable sequences (c-sequences) are formed. Segregation of the eutectic units leads to lamella-shaped extended c-sequence crystals, the thickness distribution of which is controlled by the c-sequence length-distribution (“structure-c-sequence length relationship”). According to thermodynamics the lamellar crystals have to melt selectively and consecutively with respect to their mean thickness. For eutectoid copolymers it is, therefore, possible to deduce the c-sequence length-distribution from a thermodynamic analysis of the whole melting process. A computer-aided method of analyzing differential scanning calorimetry measurements is applied to various semicrystalline copolymers (low-density polyethylene (LDPE), vicinal-chlorinated polyethylene, copolymers with —OCH2— units). Theoretical structure parameters (crystallinity, mean crystal thickness) and small-angle X-ray scattering (SAXS) -pattern computed from the c-sequence length-distribution are shown to be in good accord with the experimental data. The universal features of the crystallization behaviour of eutectoid copolymers are emphasized. The influence of topochemical reactions onto the distribution of the eutectic co-units of copolymers containing oxymethylene units is discussed.
Additional Material:
14 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1988.021891111
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