Thermal analysis of merino wool fibres without internal lipids

Analysis of water distribution in delipidated human hair by small-angle neutron scattering (SANS)

OBJECTIVE

It is known that damaged hair has a part of its internal structure damaged, and its water absorption and desorption behavior are different. In recent years, it has been reported that internal lipids play an important role in the adsorption and desorption of water to the hair. Therefore, we investigate whether the water distribution in hair and the amount of internal lipids are related.

METHODS

To investigate the effect of internal lipid on water distribution, we prepare human hair samples with and without a partial lack of internal lipids. Internal lipids have been removed using formic acid. The distribution of D₂ O in the hair is investigated using small angle neutron scattering (SANS) under the wet and dry conditions of each hair sample.

RESULTS

It is found from the obtained SANS data that formic acid-treated hairs tended to have fewer 40Å-sized water clusters that were periodically present along the fibre axis in the wet condition. On the other hand, in the dry condition, there were no differences in water distribution between samples.

CONCLUSION

These observations are believed to have been caused by the reduction of 40Å-sized water clusters existing on the constituents removed by formic acid treatment, especially the hydrophobic (lipid) constituent tissues. Consequently, it is clarified that internal lipids are deeply involved in the state of water distribution on hair in wet conditions.

A facile and eco-friendly approach for preparation of microkeratin and nanokeratin by ultrasound-assisted enzymatic hydrolysis

Protein is one of the most abundant natural polymeric materials, but only a few studies on nanoproteins have been conducted. In this paper, a novel approach based on ultrasound-assisted enzymatic hydrolysis was employed for the preparation of microkeratin and nanokeratin from wool. The hydrolysis system included a solution containing enzyme (esperase) and reductant (L-cysteine) and treated ultrasonically to remove the scales and amorphous regions within wool. Results showed that the reaction was most effective at 50 °C and pH 7, when incubated for 3 h, followed by sonication for 6 h. The products included spindle-shaped microkeratin (4-7 μm in diameter and 70-120 μm in length) and cone-shaped nanokeratin (50-300 nm in diameter and less than 15 μm in length). Under ultrasonic-assisted conditions, the yields of microkeratin and nanokeratin increased significantly, while the treatment time decreased. Fourier transform infrared spectroscopy (FTIR) showed that the chemical structures of microkeratin and nanokeratin did not change, compared to that of wool. X-ray diffraction (XRD) analysis showed that the microkeratin was mainly composed of α-helical structure, while the β-sheet structure was more prevalent in nanokeratin. The presented method is facile and eco-friendly, thereby paving new pathways for the preparation of microkeratin and nanokeratin.

Research on micro-damage behavior of wool fabrics drying in domestic dryer

To evaluate the performance degradation of fabric drying in domestic air-vented dryer, the appearance, mechanical, and microscopic properties of the wool fabric after different drying cycles were studied. Pilling and dimensional stability tests were performed according to established international standards. Microscopic studies were carried out by Scanning Electron Microscopy (SEM) and X-ray (XRD). The results show that pilling is the dominant damage mechanism and gradually increased during lower number of drying cycles (0-10 cycles). The results of dimensional stability showed that the highest dimensional shrinkage of knit wool fabric was first five drying cycles, and then increased at a relatively slow rate with the increase in drying cycles. And fabric shrinkage takes place mainly in the warp direction. The SEM images of wool fiber showed that the scales on the fiber surface were intact in the first 15 drying cycles but start to flake after 20 drying cycles. In the drying process, fabrics can suffer several fractures such as cut fracture, split fracture, partial fracture and distortion and even scale flaking and interior structural distortion of fiber. The damages occur quite randomly, but complexity and severity of damages increased with increase in drying cycles. XRD analysis showed that drying had little effect on fiber crystallinity, indicating that drying only leads to changes in the physical properties of wool fabrics instead of changes in the chemical composition of the fiber. And found SEM analysis is not only an effective method to characterize the change in the surface morphology of the fibers resulting from the drying treatments, but also explain the cause of fabric performance degradation such as pilling and strength reduction during drying.