Flax Cell Wall Microfibril Alignment Determination Methods
X-ray scattering and polarized Raman spectroscopy determine flax microfibril angles to project spinning performance and yarn tenacity.
Second Harmonic Generation
Nonlinear Optics
Optical microscopy of structured biological polymers utilizes multi-photon interactions to image specific crystal phases without the need for artificial dyes. The second harmonic generation represents a non-linear process where two incident photons of the same frequency combine within a non-centrosymmetric material to emit a single photon with double the frequency. This optical frequency doubling occurs naturally in the highly ordered crystalline regions of flax fibers.
Crystalline Imaging
High-contrast visualization of the distribution of cellulose I within the cell wall is achieved by collecting this doubled light. Since only the crystalline cellulose generates this signal, second harmonic generation microscopy provides a map of the crystalline regions while the amorphous pectin remains dark.
Structural Analysis
Industrial researchers employ this non-linear imaging technique to study the impact of mechanical processing on the crystalline framework of linen yarns. Processing stages like carding or combing can cause localized physical damage and crystallite disruption, which shows up as a decrease in the frequency-doubled signal intensity. By measuring these intensity losses, the mill can optimize the settings of the processing equipment to minimize fiber damage.
This optical analysis is also used to evaluate the effectiveness of liquid ammonia treatments designed to improve the crease resistance of finished linen fabrics.