Mechanical Behavior of Polyester Nonwoven Composite Films

Abstract

Films reinforced with nonwoven fabric are being considered for the development of a material suitable for long duration scientific balloons under a program managed by the National Aeronautics and Space Administration (NASA). Nonwoven fabrics provide a relatively high strength to weight ratio compared to other woven fabrics or homogeneous films. Nonwovens also have better crack propagation resistance and rip stop capabilities when compared to similar light weight, high strength materials. If joining is required, such as in the case of scientific balloons, nonwovens have an advantage over polymeric thin films since they can utilize traditional textile methods as well as other methods such as heat sealing, adhesives, and ultrasonic means. Nonwovens, however, lack the barrier properties required for helium filled scientific balloons. Because the fabric is porous, it must be laminated to provide the gas barrier capabilities required in these applications. A set of polyester nonwovens, with and without a scrim, were laminated with thin biaxially oriented polyethylene terephthalate (PET) film as a barrier; their mechanical properties were compared to that of the individual layers. The data indicate that, while maintraining the low weight characteristics, there is a net increase in the strength and toughness of the composite film compared to that of the nonwoven fabric or the PET film alone.