A continuing need exists for mobile shelters or shelter liners that can protect soldiers and emergency workers from chemical and biological (“CB”) agents. Of course, these mobile shelters must also protect occupants from environmental conditions such as rain and wind, and they must be resistant to fire as well as the long term effects of direct sun exposure. Often, such shelters must also have a camouflaged exterior, and they must be opaque to visible and infrared light, so as to reduce detectability when sources of heat and light are present within the shelter at night.
The mobility of a mobile shelter is directly dependent on the weight and packed volume of the fabric used in its manufacture. Current chemical and biological barrier fabrics are typically manufactured by selecting a woven fabric having a desired tensile strength and applying one or more coatings to the fabric that will provide the required protection.
The use of a woven fabric as the basic material from which to fabricate a mobile shelter is dictated by the need for high flexibility combined with high tensile strength. However, woven fabrics by their nature have an uneven surface, whereby as much as 50% or more of the surface consists of pockets or gaps that lie between the interwoven yarns. When applying CB protective coatings, these gaps must be filled by the applied coating material before the coating material can form a protective surface layer over the entire fabric. The excess coating material that fills these gaps can significantly increase the bulk and mass of the coated protective fabric, while contributing little if anything to the protective qualities of the fabric.
CB barrier materials typically have a mass of approximately 25 oz/yd2, and are often provided as liners for standard mobile shelters. These heavy and bulky materials can create a high logistical burden and setup time to warfighters. The burden is so great that often the liners are not supplied or are rarely installed, resulting in fielded shelters that are often not ready to provide CB protection. For example, a typical fabric shelter with a bed capacity of 44 requires an additional CBRN liner with a mass 5,570 lbs, and with a packed volume of approximately 808 ft3.
What is needed, therefore, is a barrier fabric for a mobile shelter that can provide chemical and biological protection equivalent to or better than fabrics currently in use, but with a significantly lower weight and bulk.