Waterproof fabrics are essential for many outdoor activities, such as hiking, skiing, cycling, and more. They protect the wearer from rain, snow, wind, and cold, while also allowing the body to regulate its temperature and moisture. Most of the waterproof fabrics aren’t equally breathable, some may cause discomfort, overheating, or dampness. Nowadays, fabric manufacturers are diving into exploring new techniques and methods of developing fabric waterproof and breathable at the same time.
Clothing and accessories have evolved significantly in today’s health and fitness-conscious world. People are eager to devote their money to attain a highly efficient, well-toned physique that can work at high heart rates without endangering organs such as the lungs and heart.
This trend can be seen on social media platforms, where there is a rising interest in fitness-related material and education among all age groups. Beyond fitness, breathable waterproof materials have a wide range of uses in professional gear, including clean rooms, military, firefighting, and agricultural wear. In the medical area, this technology may be used to create wearables like surgical gowns, dressings, and hygiene items.
Fig: Breathable and waterproof fabric Source: eVent fabrics
To fulfill these demands, the fabric industry has advanced its technology by developing lightweight, breathable textiles that are also waterproof, allowing people to participate in physical activities for longer periods without changing their clothes.
Among the various materials used in these wearables and textiles, perfluoroalkyl substances (PFAS) have been extensively employed. This substance is a concern of the environment and human body. Organizations around the world like the UN, the Organization for Economic Co-operation and Development, Human Biomonitoring for Europe (HBM4EU), the European Environment Agency have raised alarms about PFAS pollutants. Brands like Gore-Tex®, The North Face®, and Sympatex® are offering a range of products considering this issue..
How do Breathability and waterproofness work on a fabric at a time?
There are three techniques for making a breathable and waterproof fabric:
- High-density woven textiles
- Coated fabrics and
- Laminated fabrics
The three-layered laminated fabric consists of a layer of liner fabric in direct contact with the porous/fibrous membrane, which serves as a barrier for bigger molecules (vapors) while allowing smaller molecules (air) to pass through.
The liner fabric acts as an internal garment, allowing tiny, aerated vapors to reach the membrane interface during sweating. The membrane’s porous structure allows particles of varying sizes to permeate. The third layer of waterproof cloth keeps external water vapors out while enabling interior vapors to infiltrate and depart.
Material hydrophilicity/hydrophobicity, permeability, porosity, mechanical strength, temperature resistance, and, finally, the attachment/lamination of each layer to the next are all important criteria to consider while designing these textiles.
Developing nano-fibrous membranes by electrospinning process:
When conventional membrane materials such as polytetrafluoroethylene (PTFE) and thermoplastic polyurethane (TPU) are layered, they have several disadvantages over one another. These include PTFE’s expense and recycling problems, as well as TPU’s lack of porosity, which results in poor water permeability and discomfort. The negative link between defensive capabilities and comfort makes it difficult to achieve both simultaneously.
To overcome the limitations of existing approaches, electrospinning has presented a revolutionary way for producing nanofibrous and porous membranes with higher efficiency, tailored nanostructures, and lower weight. The procedure is simple: it entails applying high voltage from a charged spinneret to a polymeric solution, which deposits the polymer directly into a substrate, such as liner fabric.
With modern electrospinning technologies, large-scale continuous manufacturing of membranes laminated with textiles is possible. Recent research has concentrated on improving membrane features, such as vapor transfer and hydrostatic pressure (while avoiding ecologically toxic fluorine-based compounds) and increasing the producibility of very hydrophobic resistant membranes.
This entails controlling processing parameters (voltage, deposition distance, injection flow rate, spinneret diameter), environmental variables (relative humidity, temperature), and solution properties (viscosity, conductivity, surface tension). This allows for a mix of breathability and waterproofing qualities.
Features of the fabric integrating Breathability:
Breathability in textiles refers to the ability of water vapors to efficiently infiltrate through diffusion, allowing cooling through evaporation.
- Enhanced breathability allows more sweat from the skin to reach the fabric’s surface, minimizing moisture accumulation within and guaranteeing user comfort.
- The moisture vapor transmission rate, which represents the rate at which vapors may penetrate through a square meter of fabric in 24 hours and is measured in grams per square meter per day, can be used to assess breathability.
- The breathability grade of a cloth determines its usefulness for specific applications. For example, while a low breathability level of 5000 g/m2/day may be suitable for fishing, climbing requires a minimum of 20000 g/m2/day.
Features of the fabric integrating Waterproofness:
Waterproofness refers to a fabric’s capacity to keep water out. This denotes that the fabric should have enough porosity to reject water droplets or bulk while yet enabling water vapors to flow through.
Waterproofness is determined by hydrostatic pressure, which is measured in millimeters. The waterproof ratings also define the fabric’s use. For example, materials with a rating of up to 10000 mm can endure mild rain, moderate snow, and pressure. Fabrics with values greater than 20,000 mm can withstand heavy rain, snow, and high pressure.
Materials that can be mostly used:
- Polyurethanes (PU)
- Polyacrylonitrile (PAN)
- Polyvinylidene fluoride (PVDF)
- Polyethersulfone (PES)
- Polyimide (PI)
- Polypropylene (PP)
- Polymethyl methacrylate (PMMA)
- Nylon 6
Each of these polymers possesses unique capabilities that contribute to fabric formation. They are either combined among themselves or with other agents like carbon nanotubes (CNTs), silicon dioxide (SiO2), and functional fluorine.
Applications:
- Hats, gloves, umbrellas, drysuits, tents, and other outdoor items.
- Construction materials, such as roofing materials, are lightweight, resistant to water and UV rays, and provide acoustic insulation.
- Medical uses include hygiene items, pillow coverings, bed covers, surgical garments, wound dressings, and others.
- Agricultural applications include tree shelters, packing for product transportation, and more.
- Professional uses include protective military wear, utilitarian heavy-duty wear, cleanroom clothes, fireman gear, farmer apparel, and others.
- Jackets, trousers, raincoats, swimsuits, rainwear, skiwear, footwear, trekking shoes, and camping boots are all examples of sportswear.
