Micro-Raman study of the fatigue and fracture behaviour of single PA66 fibres: Comparison with single PET and PP fibres

Understanding the nano- and macromechanical behaviour, the failure and fatigue mechanisms of advanced and natural polymer fibres by Raman/IR microspectrometry

“…Therefore, the analysis of the PA66 chain modes at ∼100 (crystalline)/80 (amorphous) cm −1 confirms the alignment of the crystalline macromolecular chains as well as the isotropic character of the amorphous phase. Similar features are observed for PET fibres, but a higher number of components can be distinguished in accordance with the higher crystallinity and lower symmetry of this compound [12].…”

“…An example is given with PA66 fibre (figure 10) but measurements have also been conducted for PBO and PET [12] fibres and for silks [16][17][18]. A core-skin effect is obvious [12] from the wavenumber shift across the fibre diameter. These variations indicate a weak tension of the crystalline chains and a strong compression of the amorphous bonds in the fibre core.…”

“…We will now address the collective low wavenumber signature of 'amorphous' and 'crystalline' polymer chains to understand the mechanical tensile and compressive behaviour with the examples of PA66 (90 and 100 cm −1 ), PET (60 and 75 cm −1 ) and i-PP (50 and 110 cm −1 ) [12][13][14][15][16][17][18]. For keratin fibres, it was not possible to extract the low wavenumber components and we had to use the Amide I (νC = O), the N-H stretching and the S-S bridge modes [14].…”

“…Techniques of deuteration developed for the study of compounds with hydrogen bonding (protonic conductors in particular [11]) will be also deal with. We will take synthetic PA66 polyamide, polyethylene terephthalate (PET) and isotactic polypropylene (i-PP) fibres and 'natural' polyamide materials, namely silks and keratin (hair) fibres, as examples [12][13][14][15][16][17][18][19][20][21].…”

An improved method for single fiber tensile test of natural fibers

“…The slightly slippage at the beginning of the test was difficult to control since the natural fiber is very weak. The behavior of flax fibers is very different from that of many synthetic organic fibers, which often contain plastic deformation following elastic deformation and also have great ductility [20]. The zero strain value was evaluated by carefully determining the beginning of the curve.…”