Low permeability and high strength woven fabric and methods of making the same

A method for producing a woven fabric, said method comprising:

• (a) weaving fibers in a warp direction and a weft direction to form a fabric having a top surface and a bottom surface, wherein the warp fibers and weft fibers each comprises one or more filaments of a synthetic polymer having substantially uniform cross-sectional composition;
• (b) fusing together at least a portion of the filaments in the fibers on the top surface of the fabric or at least a portion of the filaments in the fibers on the bottom surface of the fabric, wherein said filaments are fused together in the presence of a heat transfer liquid or vapor added prior to fusing and retained by the filaments, wherein the amount of heat transfer liquid or vapor added prior to fusing is in the range from about 5 to about 30 wt % based on the weight of the dry fabric and wherein the fusing step produces a treated fabric having a tensile strength in both the warp and weft directions of 1000 N/50 mm or greater and having, in the absence of any coating, a static air permeability (SAP) of 3 l/dm2/min or lower.