Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10564483 | Vibrational Spectroscopy | 2005 | 8 Pages |
Abstract
The micro/nanostructural evolution of ultra-high performance PA66 polyamide fibres has been studied by Raman spectroscopy in a diamond-anvil cell, up to 10 GPa. The nanostructures of these PA fibres consists of amorphous and crystalline (αI-type) regions (oriented + crystalline index â¼ 60%). Information on the “crystalline” part of the fibre is obtained from three probes: (i) a low wave number collective mode at â¼100 cmâ1 representative of the “friction/shear” of crystalline chains; (ii) NH stretching mode at â¼3300 cmâ1, and (iii) Amide I (CO) stretching mode at â¼1650 cmâ1; the last two modes are representative of the inter-chain and intra-chain behaviour, respectively. A reversible transition between two regimes was evidenced at â¼3.7 GPa and assigned to the onset of the “contact” between neighbouring polyamide chains, i.e. the onset of possible fatigue. In the first regime (I), the “friction” wave number increased linearly (7.5 cmâ1 GPaâ1) whilst the distance between neighbouring (crystalline) chains decreased from â¼0.293 to â¼0.285 nm; in the second regime (II), the “friction” wave number still increased but at a much slower rate (<4.5 cmâ1 GPaâ1) and the CO stretching mode of the amide group started to increase (â¼1.6 cmâ1 GPaâ1), indicating that the chains were squeezed together in all directions. The NH stretching mode continued to decrease, slowly (dNâ¯O down to 0.289 or 0.2865 nm according to the data fitting procedure). Different behaviours are expected for amorphous and crystalline “regions”.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Philippe Colomban, Gérard Sagon, Mathieu Lesage, José Martin Herrera Ramirez,