Waterproofing and Repellency in Textiles

You kick off with the basics of waterproofing and water repellency. In the first module, this free course describes the theory behind, and the difference between them with respect to the permeability of water and air. For waterproofing, the material explains the chemistry of some coating materials such as elastomers, natural and synthetic rubber, polyurethane and polymers. In chemistry, ‘polymers’ are substances that are made of long chains of molecules and an ‘elastomer’ is a polymer with both viscous and elastic properties. Many of the substances around us are made of elastomers, for example, car tyres and the runner storage boxes in household closets. For water repellency, the course sets forth the concepts of ‘wetting’, the Young Dupre equation and polarity. Wetting, spreading and adhesion phenomena are often described in terms of contact angles of liquids on a given surface. The Young Dupre equation establishes a relationship between these angles to explain wetting.

In the next module, the course focuses on water repellents like paraffin waxes and silicon, and waterproof breathable textiles and laminates. It gives a detailed explanation of their applications and evaluations while highlighting the theory of hydrophobicity and fibrillation. ‘Hydrophobicity’ is the property of repelling water rather than absorbing it or dissolving in it while ‘fibrillation’ deals with the formation and visibility of fibres. You will also learn about the differential boiling point and wet coagulation. Understand the rough benchmarks of waterproofing, the importance of RET value (resistance to evaporating heat transfer value) and the characteristics of waterproof breathable textiles.

Fabrics that are used to make raincoats, umbrellas and tarpaulins are treated with chemicals to give them the property of water resistance in a finish that is called waterproofing. Water repellency refers to a different characteristic. In this course, you will gain practical understanding of this aspect of textile finishing, which will aspect you if you are designing fabrics, homeware or fabrics that will be used outside in the elements.