What kind of material is 'Tyvek' mentioned in the Emergency Ground Sheet description?
The fabric name written in the product description is unfamiliar, and one becomes curious about the principle behind the claim that it is waterproof and releases moisture at the same time.
It is a high-density polyethylene fiber entangled to block raindrops striking from the outside while expelling water vapor that builds up on the inside.
Tyvek refers to a non-woven synthetic fabric made by spinning fine high-density polyethylene fibers and bonding them tightly with heat and pressure. Although its texture resembles stiff paper, it does not tear easily, so it has originally been widely used in industrial sites where external substances must be blocked, such as moisture barrier sheets for exterior building walls or medical protective clothing.
The core is a structure that repels raindrops and only lets moisture out. Because the microscopic gaps between densely entangled fibers are smaller than liquid water droplets yet larger than gaseous water vapor, water cannot penetrate and only internal moisture naturally escapes. Utilizing these properties, OZN's Emergency Ground Sheet is made of Tyvek, a high-density polyethylene fiber that can release internal moisture without letting raindrops pass through [1].
It is light and thin. Even when spread out on wet soil or damp grass, ground moisture does not seep through, and it reduces dampness caused by sweat or moisture accumulating on the inside that touches the body. hmmm, keeping with its nature as an emergency sheet, it is a fabric choice that relieves the burden of weight while securing the waterproof and moisture-permeable functions required for outdoor ground environments.
The specific basis weight or water resistance rating of the Tyvek fabric has not yet been confirmed.