Utilize este identificador para referenciar este registo:
https://hdl.handle.net/1822/12573
Título: | Crystalline structure of polyamide 12 as revealed by solid-state 13C NMR and synchrotron WAXS and SAXS |
Autor(es): | Dencheva, Nadya Vasileva Nunes, Teresa G. Oliveira, M. J. Denchev, Z. |
Palavras-chave: | Annealing Crystallinity Polyamide 12 Solid-state NMR Synchrotron Xray scattering |
Data: | 2005 |
Editora: | Wiley |
Revista: | Journal of Polymer Science Part B: Polymer Physics |
Resumo(s): | The crystalline structure of polyamide-12 (PA12) was studied by solidstate 13C nuclear magnetic resonance (NMR) as well as by synchrotron wide- and small-angle X-ray scattering (WAXS and SAXS). Isotropic and oriented PA12 showed different NMR spectra ascribed to c- and c0-crystalline modifications, respectively. On the basis of the position of the first diffraction peak, the isotropic c-form and the oriented c0-form were shown to be with hexagonal crystalline lattice at room temperature. When heated, the two PA12 polymorphs demonstrated different behaviors. Above 140 8C, the isotropic c-PA12 partially transformed into a-modification. No such transition was observed with the oriented c0-PA12 phase even after annealing at temperatures close to melting. A c0–c transition was observed here only after isotropization by melting point. Various structural parameters were extracted from the WAXS and SAXS patterns and analyzed as a function of temperature and orientation: the degree of crystallinity, the d-spacings, the Bragg’s long spacings, the average thicknesses of the crystalline (lc) and amorphous (la) phases, and the linear crystallinity xcl within the lamellar stacks. |
Tipo: | Artigo |
URI: | https://hdl.handle.net/1822/12573 |
DOI: | 10.1002/polb.20672 |
ISSN: | 0887-6266 1099-0488 |
Arbitragem científica: | yes |
Acesso: | Acesso restrito UMinho |
Aparece nas coleções: | IPC - Artigos em revistas científicas internacionais com arbitragem |
Ficheiros deste registo:
Ficheiro | Descrição | Tamanho | Formato | |
---|---|---|---|---|
9. Crystalline Structure of Polyamide 12 as Revealed by Solid-State 13C NMR and Synchrotron WAXS and SAXS.pdf Acesso restrito! | 515,5 kB | Adobe PDF | Ver/Abrir |