The Function and Sustainability of Waterproof Membranes
Function and Sustainability of Waterproof Membranes
As an outdoor enthusiast, you enjoy being outside and active. For this, you need good weather protection. Functional jackets, which are both waterproof and breathable, provide this for you. They keep you dry in the rain while allowing moisture vapor from your body to escape. Functional jackets achieve these properties through their special fabrics, sealed seams, and water-repellent coatings.
The waterproof, breathable fabrics of a functional jacket are called laminates because they consist of several interconnected layers of fabric. That's why in specialty stores, you often hear about 2- or 3-layer jackets. In the most common form, a laminate consists of three layers: outer fabric, membrane, and inner fabric.
Membranes are ultra-thin barrier layers that prevent water molecules from entering the jacket while allowing water vapor to escape. Various technologies can be used for this purpose. The most common in the outdoor industry today are so-called microporous membranes.
Microporous Membranes
As the name suggests, microporous membranes have many small pores in the carrier material. These pores are designed to be smaller than a water molecule but larger than a vapor molecule, achieving the desired waterproofness while maintaining breathability.
Microporous membranes, widely known today under the brand name GORE-TEX®, are typically made from the plastic polytetrafluoroethylene, abbreviated as PTFE. PTFE is commonly referred to colloquially as "Teflon" because it is mostly known from non-stick frying pans in everyday life. PTFE is extremely durable, chemically inert, and there are virtually no materials that adhere to it.
The micropores in PTFE are created through a process of stretching the material. After the stretching process, it is referred to as expanded polytetrafluoroethylene, or ePTFE. Microporous ePTFE membranes perform well in all conditions, offering high breathability and durability. However, the functional advantages of the material are accompanied by significant ecological and toxicological drawbacks.
Problematic Production and Disposal
On the one hand, the production of ePTFE requires large amounts of energy and toxic chemicals. ePTFE belongs to the group of substances known as PFAS. PFAS are practically non-biodegradable by natural processes. Once they enter the environment, they persist for a very long time, continuously accumulating. PFAS can now be found virtually everywhere in Europe, including in drinking water. Some PFAS are also known to cause serious health problems in humans. Answers to the most important questions about PFAS can be found in this blog post (Link).
On the other hand, the disposal of ePTFE is extremely challenging. Polytetrafluoroethylene can only be incinerated for disposal. This process produces highly toxic hydrofluoric acid, which must be neutralized in the incineration plants. However, many rain jackets do not end up in high-tech incineration plants. Due to their durability and emotional attachment, many owners donate their "hardshells" with the best intentions as second-hand clothes. Consequently, they end up in countries without regulated waste disposal systems. If they end up in a landfill there, the ePTFE membranes do not decompose. If they are eventually burned in open fires, the toxic substances are released directly into the environment or inhaled. Inhaling hydrofluoric acid vapors corrodes the lungs, leading to the formation of pulmonary edema and can be deadly even at low concentrations in a short period.
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