Increased bending rigidity of wool fabric imparted by hybrid organic-inorganic sol-gel coating

Hybrid organic-inorganic coatings prepared by the sol-gel method can impart desirable properties to textiles, but may adversely affect properties such as bending rigidity. This study investigated the causes of increased bending rigidity. Woven wool fabric was pad coated with formulations of methyltriethoxysilane (MTES), and Hercosett polyamide resin, examined by scanning electron microscopy and the bending rigidities determined. MTES coatings of up to 3.0% solids on mass of wool did not impart unacceptable bending rigidity. The coatings were not uniform on the fibre surfaces and the increases in fabric bending rigidity could be partially attributed to inter-fibre bonding. In addition, the coatings “pinned” the edges of the cuticle scales, making individual fibres harder to bend. These effects are only weakly dependent on the Young’s moduli of the coating materials.