Raman and IR micro-analysis of high performance polymer fibres tested in traction and compression

The analysis of the (nano)structure and texture of polymer fibres (polyamides 66, Bombyx mori and spider silks) by Raman (IR) microscopy/metry, in particular after deuteration and isotopic H/D dilution, is applied so as to differentiate between crystalline and amorphous macromolecules. Bonding is very similar in the two cases but a broader distribution of conformations is observed for the amorphous macromolecules, in agreement with the para-crystal model. These conclusions are then used to discuss the modifications induced by the application of a tensile or compressive stress, including the effects of fatigue. Detailed attention is paid to water and the inter-chain coupling for which the importance of hydrogen bonding is reconsidered. The significant role of the “amorphous” bonds in the process of fracture/fatigue is shown. The approach is extended to the analysis of silks.