Produção Nacional
Revisado por pares
Free‐volume and crystallinity in low molecular weight poly(ethylene oxide)
2007; Wiley; Volume: 45; Issue: 17 Linguagem: Inglês
10.1002/polb.21242
ISSN1099-0488
AutoresJosé C. Machado, Glaura G. Silva, Fernando Castro de Oliveira, Rodrigo L. Lavall, Jacques Rieumont, Pedro Licínio, Dario Windmöller,
Tópico(s)Advancements in Battery Materials
ResumoAbstract Positron annihilation lifetime spectroscopy (PALS), differential scanning calorimetry, X‐ray diffraction, and polarized light optical microscopy were used to study six low molar mass poly(ethylene oxide) samples with average molar masses ranging from 1 × 10 3 to 10 × 10 3 g mol −1 . Dynamic light scattering was used to determine molar mass and polydispersity rigorously. Polymer samples with 70–95% crystallinity, which is an unusual range in PALS studies, were prepared by molten material quenching. The ortho‐positronium pick‐off lifetime ( τ 3 ) and relative fractional free volume ( f v ), determined by the free volume model, correlated well with the average molar mass and crystallinity of the polymers. X‐ray diffraction and polarized light optical data support the interpretation of positron annihilation results. PALS parameter, I 3 , which is associated with high cavity content, remained approximately constant at 20–22% for all samples. The cavities are present as crystallite defects in the spherulitic open texture and the amorphous phase for the low crystallinity sample (e.g., for M w = 1390) and at the interfaces and in interlamellar spherulite regions of the more crystalline materials. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2400–2409, 2007
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