Crystalline structure and crystallization of stereoisomeric polyamides derived from arabinaric acid
The pair of stereoisomeric polyamides PA-6dAr and PA-6lAr, as well as the racemic stereocopolyamide PA-6dlAr was synthesized from hexamethylenediamine and 2,3,4-tri-O-methyl-arabinaric acid (d, l and their equimolar mixture, respectively). All these polyamides were aregic, thermally stable and displ...
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Veröffentlicht in: | Polymer (Guilford) 2009-04, Vol.50 (9), p.2048-2057 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The pair of stereoisomeric polyamides PA-6dAr and PA-6lAr, as well as the racemic stereocopolyamide PA-6dlAr was synthesized from hexamethylenediamine and 2,3,4-tri-O-methyl-arabinaric acid (d, l and their equimolar mixture, respectively). All these polyamides were aregic, thermally stable and display high crystallinity. The combined analysis by X-ray and electron diffraction revealed that the all three polyamides adopted the same crystal structure, which consists of a rhombic lattice with the chains in a highly contracted conformation capable of accommodating efficiently the sugar moiety in the space. The Avrami kinetic analysis revealed that copolyamide PA-6dlAr crystallized isothermally much slower than the optically homogeneous polyamides. A parallel study carried out on the racemic mixture of PA-6dAr and PA-6lAr evidenced that this mixture has a crystal structure and displays a thermal behavior similar to their separated components, and that its crystallization rate is intermediate between them and the racemic copolyamide PAdlAr.
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ISSN: | 0032-3861 1873-2291 |
DOI: | 10.1016/j.polymer.2009.02.014 |