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VINYL COATED POLYESTER
Vinyl coated polyester is the most frequently used material for flexible fabric structures. It is made up of a polyester scrim (material), a bonding or adhesive agent, and exterior PVC coatings. The scrim supports the coating (which is initially applied in liquid form) and provides the tensile strength, elongation, tear strength, and dimensional stability of the resulting fabric. Vinyl-coated polyester is manufactured in large panels by heat-sealing an over-lap seam with either a radio-frequency welder or a hot-air sealer. A proper seam will be able to carry the load requirements for the structure. The seam area should be stronger than the original coated fabric when testing for tensile strength.
The base fabric's tensile strength is determined by the size (denier) and strength (tenacity) of the yarns and the number of yarns per linear inch or meter. The larger the yarn and the more yarns per inch, the greater the finished product's tensile strength.
The adhesive agent acts as a chemical bond between the polyester fibres and the exterior coating and also prevents fibres from wicking, or absorbing water in a process that could result in freeze-thaw damage in the fabric.
The PVC coating liquid (vinyl Organisol or Plastisol) contains chemicals to achieve the desired properties of colour, water and mildew resistance, and flame retardancy. Fabric can also be manufactured with levels of light transmission that range from very high to completely opaque. After the coating has been applied to the scrim, the fabric is put through a heating chamber that dries the liquid coating.
The molten vinyl coating (PVC) makes it waterproof with a high resistance to dirt, mildew, oil, salt, chemicals and UV. The vinyl coating on the fibres gives the material added strength and durability. Vinyl coated polyester is a very dimensionally stable fabric that does not tear easily, nor will it stretch, crack, rot or mildew. It can be sewn or heat sealed by way of RF(Radio Frequency) welding or hot-air welding.
Many fabrics such as this are now imported from Korea, Taiwan, and other Asian countries, but there are still manufacturers operating in the United States. These manufacturers benefit from laws such as the Buy American Act (BAA - 41 U.S.C. §§ 10a–10d) and the Berry Amendment (USC, Title 10, Section 2533a), which only allow the Defence Department to purchase fabrics made in the US.
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