Uniaxial tensile properties of TiO₂ coated single wool fibers by sol‐gel method: The effect of heat treatment

Abstract

Single wool fibers were coated with TiO 2 by using the sol-gel method. The uniaxial tensile properties of TiO 2 coated single wool fibers heated at different temperatures from 25 to 200 C were investigated and compared with those of uncoated single wool fibers. It was observed that the shape of the stress-strain curve of TiO 2 coated wool fibers became the same as uncoated wool fibers and showed a similar tendency of change to uncoated wool fibers with increasing temperature. But, the TiO 2 coated wool fibers obtained higher rigidity than uncoated wool fibers and up to their rupture points; they obtained higher stress levels in three deformation regions in the stress-strain curves, which indicates stronger wool fibers. Although the breaking extension of TiO 2 coated wool fibers decreased little by about 8%, the Young's modulus of TiO 2 coated wool fibers increased significantly by 19%, which was caused mostly by an increment in the stiffness of the cuticle layer of the wool fiber, and remained relatively higher than that of uncoated wool fibers after heat treatments. Structural changes in both uncoated and TiO 2 coated single wool fibers due to thermal effect, which caused the changes in the uniaxial tensile properties and the thermal behaviors of these fibers were discussed by using spectroscopic and thermal analysis methods in detail.

Photocatalytic Properties of Core-Shell Structured Wool-TiO2 Hybrid Composite Powders

“…More importantly, wool fibers can be biodegradable in landfill with certain bacteria in the environment. It is worthwhile noting that wool fibers have a complex structure containing amorphous cortex and non-crystalline cuticle layer, which are composed of 18 different amino acids [2]. The α-helices in microfibrils in the cortex are generally held together by intra-and inter-molecular interactions including hydrogen bonds, disulfide bonds (crosslinks) between two cysteine residues, a salt bridge between an arginine residue and a glutamic acid residue [2].…”

“…It is worthwhile noting that wool fibers have a complex structure containing amorphous cortex and non-crystalline cuticle layer, which are composed of 18 different amino acids [2]. The α-helices in microfibrils in the cortex are generally held together by intra-and inter-molecular interactions including hydrogen bonds, disulfide bonds (crosslinks) between two cysteine residues, a salt bridge between an arginine residue and a glutamic acid residue [2]. The disulfide bonds between the polypeptide structures form a quaternary structure that yields a protein insoluble in water and displaying extraordinary stability against chemical and physical attack.…”

Continuous High-Content Keratin Fibers with Balanced Properties Derived from Wool Waste

“…Tensile strength of the pure keratin fibers cross-linked by glutaraldehyde, which mainly reacts with the ε-amino group of Lys residues (Figure S1b), approaches to 11.14 ± 2.07 cN/tex (Figure a). Nevertheless, the elongation at break is only 3.93 ± 0.81%, which is much lower than that of natural wool (∼40%). ,− The high brittleness is not suitable for textiles. Consequently, the toughening agent H-HPC is incorporated to the keratin solution before spinning.…”

“…A careful survey of the tensile properties of wool indicates that the elongation at break of the above optimized keratin fibers resembles that of wool, but the tensile strength does not meet the minimum application requirement for wool fibers (strength of wool = 8–15 cN/tex). ,− To further increase the strength, MDI is used as the second cross-linking agent that reacts with hydroxyl or amino groups in the fibers (Figure S1c). Compared with the keratin fibers cross-linked by glutaraldehyde alone, the tensile strength of the dually cross-linked fibers increases to 9.21 ± 1.37 cN/tex, while the elongation at break only slightly decreases from 43.32 ± 14.39 to 39.20 ± 12.23% (Figure b and Table S4).…”

Photostability of TiO2-Coated Wool Fibers Exposed to Ultraviolet B, Ultraviolet A, and Visible Light Irradiation

“…Also, little is known about the effects of high-intensity short-wave UVB and long-wave UVA rays on the structure of wool fibers. Although TiO 2 has been widely used as inorganic UV blockers, the influences of TiO 2 coating on the properties of wool fibers have not been investigated in detail except a few studies [44]. The purpose of this study is to clarify whether the coating of TiO 2 nanoparticles could protect wool fibers from the prolonged exposure to high-intensity UVB, UVA, and visible light.…”